View source for 3D printing

{{Short description|Additive process used to make a 3D object}}
{{About|| methods of transferring an image onto a 3D surface|pad printing|methods of generating autostereoscopic lenticular images|lenticular printing|and|holography}}
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{{Use dmy dates|date=December 2019}}
{{EngvarB|date=May 2014}}
[[File:Robot 3D print timelapse on RepRapPro Fisher.webm|thumb|[[Timelapse]] of a three-dimensional printer in action]]
{{History of printing}}

'''3D printing''', or '''additive manufacturing''', is the [[Manufacturing|construction]] of a [[three-dimensional object]] from a [[computer-aided design|CAD]] model or a digital [[3D modeling|3D model]].<ref>{{Cite news|url=https://www.economist.com/technology-quarterly/2013/09/05/3d-printing-scales-up|title=3D printing scales up|date=5 September 2013|newspaper=The Economist|access-date=15 July 2019|archive-date=15 July 2019|archive-url=https://web.archive.org/web/20190715194438/https://www.economist.com/technology-quarterly/2013/09/05/3d-printing-scales-up|url-status=live}}</ref><ref>{{cite journal |last1=Gao |first1=Wei |last2=Zhang |first2=Yunbo |last3=Ramanujan |first3=Devarajan |last4=Ramani |first4=Karthik |last5=Chen |first5=Yong |last6=Williams |first6=Christopher B. |last7=Wang |first7=Charlie C. L. |last8=Shin |first8=Yung C. |last9=Zhang |first9=Song |last10=Zavattieri |first10=Pablo D. |title=The status, challenges, and future of additive manufacturing in engineering |journal=Computer-Aided Design |date=2015 |volume=69 |pages=65–89 |doi=10.1016/j.cad.2015.04.001|s2cid=33086357 | issn=0010-4485 }}</ref><ref>{{cite journal |last1=Ngo |first1=Tuan D. |last2=Kashani |first2=Alireza |last3=Imbalzano |first3=Gabriele |last4=Nguyen |first4=Kate T. Q. |last5=Hui |first5=David |title=Additive manufacturing (3D printing): A review of materials, methods, applications and challenges |journal=Composites Part B: Engineering |date=2018 |volume=143 |pages=172–196 |doi=10.1016/j.compositesb.2018.02.012|s2cid=139464688 }}</ref> It can be done in a variety of processes in which material is deposited, joined or solidified under [[Computer Numerical Control|computer control]],<ref name="engineer" /> with the material being added together (such as plastics, liquids or powder grains being fused), typically layer by layer.

In the 1980s, 3D printing techniques were considered suitable only for the production of functional or aesthetic prototypes, and a more appropriate term for it at the time was [[rapid prototyping]].<ref>{{Cite web|url=https://www.tmg-muenchen.de/training-course/11/Additive-Manufacturing?flang=en|title=Learning Course: Additive Manufacturing – Additive Fertigung|website=tmg-muenchen.de|access-date=23 August 2019|archive-date=23 August 2019|archive-url=https://web.archive.org/web/20190823030140/https://www.tmg-muenchen.de/training-course/11/Additive-Manufacturing%3Fflang%3Den|url-status=live}}</ref> {{As of|2019}}, the precision, repeatability, and material range of 3D printing have increased to the point that some 3D printing processes are considered viable as an industrial-production technology; in this context, the term ''additive manufacturing'' can be used synonymously with ''3D printing''.<ref>{{Cite journal |last1=Lam |first1=Hugo K.S. |last2=Ding |first2=Li |last3=Cheng |first3=T.C.E. |last4=Zhou |first4=Honggeng |date=2019-01-01 |title=The impact of 3D printing implementation on stock returns: A contingent dynamic capabilities perspective |journal=International Journal of Operations & Production Management |volume=39 |issue=6/7/8 |pages=935–961 |doi=10.1108/IJOPM-01-2019-0075 |s2cid=211386031 |issn=0144-3577}}</ref> One of the key advantages of 3D printing<ref>{{Cite web |title=3D Printing: All You Need To Know |url=https://explainedideas.com/3d-printing/ |access-date=2022-08-11 |website=explainedideas.com |language=en-US |archive-date=20 August 2022 |url-status=usurped |archive-url=https://web.archive.org/web/20220820155725/https://explainedideas.com/3d-printing/ }}</ref> is the ability to produce very complex shapes or geometries that would be otherwise infeasible to construct by hand, including hollow parts or parts with internal [[truss]] structures to reduce weight while creating less material waste. [[Fused filament fabrication#Fused deposition modeling|Fused deposition modeling]] (FDM), which uses a continuous filament of a [[thermoplastic]] material, is the most common 3D printing process in use {{as of|2020|lc=y}}.<ref name="statista1"/>

== Terminology ==
The [[umbrella term]] ''additive manufacturing (AM)'' gained popularity in the 2000s,<ref name="Ngram_additive_manufacturing" /> inspired by the theme of material being added together ([[3D printing processes|in any of various ways]]). In contrast, the term ''subtractive manufacturing'' appeared as a [[retronym]] for the large family of [[machining]] processes with material ''removal'' as their common process. The term ''3D printing'' still referred only to the polymer technologies in most minds, and the term ''AM'' was more likely to be used in metalworking and end-use part production contexts than among polymer, inkjet, or stereolithography enthusiasts.

By the early 2010s, the terms ''3D printing'' and ''additive manufacturing'' evolved [[word sense|senses]] in which they were alternate umbrella terms for additive technologies, one being used in popular language by consumer-maker communities and the media, and the other used more formally by industrial end-use part producers, machine manufacturers, and global technical standards organizations. Until recently, the term ''3D printing'' has been associated with machines low in price or capability.<ref>{{Cite web|url=https://www.iso.org/standard/69669.html|title=ISO/ASTM 52900:2015 – Additive manufacturing – General principles – Terminology|website=iso.org|language=en|access-date=15 June 2017|archive-date=10 July 2017|archive-url=https://web.archive.org/web/20170710205730/https://www.iso.org/standard/69669.html|url-status=live}}</ref> ''3D printing'' and ''additive manufacturing'' reflect that the technologies share the theme of material addition or joining throughout a 3D work envelope under automated control. Peter Zelinski, the editor-in-chief of ''Additive Manufacturing'' magazine, pointed out in 2017 that the terms are still often [[synonym]]ous in casual usage,<ref name="Zelinski_2017-08-04">{{Citation |last=Zelinski |first=Peter |date=4 August 2017 |title=Additive manufacturing and 3D printing are two different things |journal=Additive Manufacturing |url=http://www.additivemanufacturing.media/columns/additive-manufacturing-and-3d-printing-are-two-different-things |access-date=11 August 2017 |postscript=. |archive-date=12 August 2017 |archive-url=https://web.archive.org/web/20170812022403/http://www.additivemanufacturing.media/columns/additive-manufacturing-and-3d-printing-are-two-different-things |url-status=live }}</ref> but some manufacturing industry experts are trying to make a distinction whereby additive manufacturing [[hyponymy and hypernymy|comprises]] 3D printing plus other technologies or other aspects of a [[manufacturing process]].<ref name="Zelinski_2017-08-04" />

Other terms that have been used as synonyms or [[hyponymy and hypernymy|hypernyms]] have included ''desktop manufacturing'', ''rapid manufacturing'' (as the logical production-level successor to ''[[rapid prototyping]]''), and ''on-demand manufacturing'' (which echoes ''[[print on demand|on-demand printing]]'' in the 2D sense of ''printing''). The fact that the application of the adjectives ''rapid'' and ''on-demand'' to the noun ''manufacturing'' was novel in the 2000s reveals the long-prevailing [[mental model]] of the previous industrial era during which almost all production manufacturing had involved long [[lead time]]s for laborious tooling development. Today, the term ''subtractive'' has not replaced the term ''machining'', instead [[wikt:complement#Verb|complementing]] it when a term that covers any removal method is needed. [[Agile tooling]] is the use of modular means to design tooling that is produced by additive manufacturing or 3D printing methods to enable quick [[Prototype|prototyping]] and responses to tooling and fixture needs. Agile tooling uses a cost-effective and high-quality method to quickly respond to customer and market needs, and it can be used in [[hydroforming]], [[Stamping (metalworking)|stamping]], [[Injection molding machine|injection molding]] and other manufacturing processes.

== History ==
=== 1940s and 1950s ===
The general concept of and procedure to be used in 3D-printing was first described by [[Murray Leinster]] in his 1945 short story "Things Pass By": "But this constructor is both efficient and flexible. I feed magnetronic plastics — the stuff they make houses and ships of nowadays — into this moving arm. It makes drawings in the air following drawings it scans with photo-cells. But plastic comes out of the end of the drawing arm and hardens as it comes ... following drawings only"<ref>M. Leinster, Things Pass By, in ''The Earth In Peril'' (D. Wollheim ed.). Ace Books 1957, USA, [[List of Ace SF double titles]] D-205, p.25, story copyright 1945, by Standard Magazines Inc.</ref>

It was also described by [[Raymond F. Jones]] in his story, "Tools of the Trade", published in the November 1950 issue of ''[[Analog Science Fiction and Fact|Astounding Science Fiction]]'' magazine. He referred to it as a "molecular spray" in that story.

=== 1970s ===
In 1971, Johannes F Gottwald patented the Liquid Metal Recorder, U.S. patent 3596285A,<ref>{{Cite web |title=US3596285A - Liquid metal recorder |url=https://patents.google.com/patent/US3596285A |url-status=live |archive-url=https://archive.today/20240305235746/https://patents.google.com/patent/US3596285A |archive-date=5 March 2024 |website=Google Patents}}</ref> a continuous inkjet metal material device to form a removable metal fabrication on a reusable surface for immediate use or salvaged for printing again by remelting. This appears to be the first patent describing 3D printing with rapid prototyping and controlled on-demand manufacturing of patterns.

The patent states:

{{blockquote|As used herein the term printing is not intended in a limited sense but includes writing or other symbols, character or pattern formation with an ink. The term ink as used in is intended to include not only dye or pigment-containing materials, but any flowable substance or composition suited for application to the surface for forming symbols, characters, or patterns of intelligence by marking. The preferred ink is of a hot melt type. The range of commercially available ink compositions which could meet the requirements of the invention are not known at the present time. However, satisfactory printing according to the invention has been achieved with the conductive metal alloy as ink.

But in terms of material requirements for such large and continuous displays, if consumed at theretofore known rates, but increased in proportion to increase in size, the high cost would severely limit any widespread enjoyment of a process or apparatus satisfying the foregoing objects.

It is therefore an additional object of the invention to minimize use to materials in a process of the indicated class.

It is a further object of the invention that materials employed in such a process be salvaged for reuse.

According to another aspect of the invention, a combination for writing and the like comprises a carrier for displaying an intelligence pattern and an arrangement for removing the pattern from the carrier.}}

In 1974, [[David E. H. Jones]] laid out the concept of 3D printing in his regular column ''Ariadne'' in the journal ''[[New Scientist]]''.<ref>{{Cite journal |date=3 October 1974 |title=Ariadne |url=https://books.google.com/books?id=nvabM3KXNsUC&pg=PA80 |archive-url=https://web.archive.org/web/20231006205006/https://books.google.com/books?id=nvabM3KXNsUC&pg=PA80 |archive-date=6 October 2023 |journal=New Scientist |volume=64 |issue=917 |page=80 |issn=0262-4079 }}</ref><ref>{{cite web | last=Ellam | first=Richard | title=3D printing: you read it here first | website=New Scientist | date=26 February 2019 | url=https://www.newscientist.com/letter/mg23230991-100-1-editors-pick-3d-printing-you-read-it-here-first/ | access-date=23 August 2019 | archive-date=17 August 2019 | archive-url=https://web.archive.org/web/20190817095138/https://www.newscientist.com/letter/mg23230991-100-1-editors-pick-3d-printing-you-read-it-here-first/ | url-status=live }}</ref>

=== 1980s ===
Early additive manufacturing equipment and materials were developed in the 1980s.<ref name="3D opp" />

In April 1980, Hideo Kodama of [[Nagoya]] Municipal Industrial Research Institute invented two additive methods for fabricating three-dimensional plastic models with photo-hardening [[thermosetting polymer|thermoset polymer]], where the [[UV exposure]] area is controlled by a mask pattern or a scanning fiber transmitter.<ref>Hideo Kodama, " Background of my invention of 3D printer and its spread", Patent Magazine of Japan Patent Attorneys Association, vo.67, no.13, pp.109-118, November 2014.</ref>
He filed a patent for this XYZ plotter, which was published on 10 November 1981. (JP S56-144478).<ref>{{Cite patent |number=JP-S56-144478 |title=JP Patent: S56-144478 - 3D figure production device |gdate=10 November 1981|inventor1-first=Hideo Kodama|url= https://www.j-platpat.inpit.go.jp/c1800/PU/JP-S56-144478/1D0ADD2064383A29D55152F0210F025DEFC37B25B70242A69D2F88F6F3A29A10/11/en}}</ref>
His research results as journal papers were published in April and November 1981.<ref>Hideo Kodama, "A Scheme for Three-Dimensional Display by Automatic Fabrication of Three-Dimensional Model", IEICE Transactions on Electronics (Japanese Edition), vol. J64-C, No. 4, pp. 237–41, April 1981</ref><ref>Hideo Kodama, "Automatic method for fabricating a three-dimensional plastic model with photo-hardening polymer", ''Review of Scientific Instruments'', Vol. 52, No. 11, pp. 1770–73, November 1981</ref>
However, there was no reaction to the series of his publications. His device was not highly evaluated in the laboratory and his boss did not show any interest. His research budget was just 60,000 yen or $545 a year. Acquiring the patent rights for the XYZ plotter was abandoned, and the project was terminated.

A US 4323756 patent, ''method of fabricating articles by sequential deposition'', granted on 6 April 1982 to Raytheon Technologies Corp describes using hundreds or thousands of "layers" of powdered metal and a laser energy source and represents an early reference to forming "layers" and the fabrication of articles on a substrate.

On 2 July 1984, American entrepreneur [[William (Bill) Masters|Bill Masters]] filed a patent for his computer automated manufacturing process and system ([https://patents.google.com/patent/US4665492 US 4665492]).<ref>{{Cite patent|number=4665492|title=United States Patent: 4665492 - Computer automated manufacturing process and system|gdate=12 May 1987|invent1=Masters|inventor1-first=William E.|url=http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=1&u=/netahtml/PTO/search-bool.html&r=1&f=G&l=50&co1=AND&d=PTXT&s1=4665492.PN.&OS=PN/4665492&RS=PN/4665492}} {{Webarchive|url=https://web.archive.org/web/20220412002851/https://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=1&u=/netahtml/PTO/search-bool.html&r=1&f=G&l=50&co1=AND&d=PTXT&s1=4665492.PN.&OS=PN/4665492&RS=PN/4665492 |date=12 April 2022 }}</ref> This filing is on record at the [[United States Patent and Trademark Office|USPTO]] as the first 3D printing patent in history; it was the first of three patents belonging to Masters that laid the foundation for the 3D printing systems used today.<ref>{{Cite web|url=https://upstatebusinessjournal.com/3-d-printing-steps-into-the-spotlight/|title=3-D Printing Steps into the Spotlight|date=2013-04-11|website=Upstate Business Journal|language=en-US|access-date=2019-12-20|archive-date=20 December 2019|archive-url=https://web.archive.org/web/20191220194129/https://upstatebusinessjournal.com/3-d-printing-steps-into-the-spotlight/}}</ref><ref>{{Cite book|url=https://books.google.com/books?id=n25nXHZ8vwMC&q=Special+Report:+Rapid+Prototyping+Systems&pg=PA149|title=Concurrent Design of Products, Manufacturing Processes and Systems|last=Wang|first=Ben|date=1999-01-27|publisher=CRC Press|isbn=978-90-5699-628-4|language=en}}</ref>

On 16 July 1984, [[Alain Le Mehaute|Alain Le Méhauté]], Olivier de Witte, and Jean Claude André filed their patent for the [[stereolithography]] process.<ref>{{cite news|url=http://bases-brevets.inpi.fr/fr/document/FR2567668/publications.html|title=Disdpositif pour realiser un modele de piece industrielle|last=Jean-Claude|first=Andre|newspaper=National De La Propriete Industrielle|access-date=5 February 2016|archive-date=5 February 2016|archive-url=https://web.archive.org/web/20160205234929/http://bases-brevets.inpi.fr/fr/document/FR2567668/publications.html|url-status=dead}}</ref> The application of the French inventors was abandoned by the French General Electric Company (now Alcatel-Alsthom) and [[CILAS]] (The Laser Consortium).<ref>{{cite web|url=http://3dprint.com/65466/reflections-alain-le-mehaute/|title=Alain Le Méhauté, The Man Who Submitted Patent For SLA 3D Printing Before Chuck Hull|last=Mendoza|first=Hannah Rose|date=15 May 2015|publisher=3dprint.com|access-date=5 February 2016|archive-date=3 February 2016|archive-url=https://web.archive.org/web/20160203220515/http://3dprint.com/65466/reflections-alain-le-mehaute/|url-status=live}}</ref> The claimed reason was "for lack of business perspective".<ref>{{Cite news|url=http://www.primante3d.com/inventeur|title=Interview d'Alain Le Méhauté, l'un des pères de l'impression (Interview of Alain Le Mehaute, one of the 3D printinf technologies fathers) 3D|last=Moussion|first=Alexandre|date=2014|newspaper=Primante 3D}}</ref>

In 1983, Robert Howard started R.H. Research, later named Howtek, Inc. in Feb 1984 to develop a color inkjet 2D printer, Pixelmaster, commercialized in 1986, using Thermoplastic (hot-melt) plastic ink.<ref name=":3">{{Cite book|last=Howard |first=Robert |title=Connecting the dots: my life and inventions, from X-rays to death rays|date=2009|publisher=Welcome Rain|isbn=978-1-56649-957-6|location=New York, NY|pages=195–197|oclc=455879561}}</ref> A team was put together, 6 members<ref name=":3" /> from Exxon Office Systems, Danbury Systems Division, an inkjet printer startup and some members of Howtek, Inc group who became popular figures in the 3D printing industry. One Howtek member, Richard Helinski (patent US5136515A, Method and Means for constructing three-dimensional articles by particle deposition, application 11/07/1989 granted 8/04/1992) formed a New Hampshire company C.A.D-Cast, Inc, name later changed to Visual Impact Corporation (VIC) on 8/22/1991. A prototype of the VIC 3D printer for this company is available with a video presentation showing a 3D model printed with a single nozzle inkjet. Another employee Herbert Menhennett formed a New Hampshire company HM Research in 1991 and introduced the Howtek, Inc, inkjet technology and thermoplastic materials to Royden Sanders of SDI and Bill Masters of Ballistic Particle Manufacturing (BPM) where he worked for a number of years. Both BPM 3D printers and SPI 3D printers use Howtek, Inc style Inkjets and Howtek, Inc style materials. Royden Sanders licensed the Helinksi patent prior to manufacturing the Modelmaker 6 Pro at Sanders prototype, Inc (SPI) in 1993. James K. McMahon who was hired by Howtek, Inc to help develop the inkjet, later worked at Sanders Prototype and now operates Layer Grown Model Technology, a 3D service provider specializing in Howtek single nozzle inkjet and SDI printer support. James K. McMahon worked with Steven Zoltan, 1972 drop-on-demand inkjet inventor, at Exxon and has a patent in 1978 that expanded the understanding of the single nozzle design inkjets (Alpha jets) and helped perfect the Howtek, Inc hot-melt inkjets. This Howtek hot-melt thermoplastic technology is popular with metal investment casting, especially in the 3D printing jewelry industry.<ref name=":4">{{Cite book|last=Barnatt|first=Christopher|title=3D printing: the next industrial revolution|date=2013|publisher=ExplainingTheFuture.com|isbn=978-1-4841-8176-8|location=[Nottingham, England?]|oclc=854672031}}</ref> Sanders (SDI) first Modelmaker 6Pro customer was Hitchner Corporations, Metal Casting Technology, Inc in Milford, NH a mile from the SDI facility in late 1993–1995 casting golf clubs and auto engine parts.

On 8 August 1984 a patent, US4575330, assigned to UVP, Inc., later assigned to [[Chuck Hull]] of [[3D Systems]] Corporation<ref name="AutoSQ-1" /> was filed, his own patent for a [[stereolithography]] fabrication system, in which individual laminae or layers are added by curing [[photopolymers]] with impinging radiation, particle bombardment, chemical reaction or just [[ultraviolet light]] [[laser]]s. Hull defined the process as a "system for generating three-dimensional objects by creating a cross-sectional pattern of the object to be formed".<ref name="AutoSQ-4" /><ref name="AutoSQ-5" /> Hull's contribution was the [[STL (file format)|STL (Stereolithography) file format]] and the digital slicing and infill strategies common to many processes today. In 1986, Charles "Chuck" Hull was granted a patent for this system, and his company, 3D Systems Corporation was formed and it released the first commercial 3D printer, the SLA-1,<ref>{{Cite web|url=https://all3dp.com/2/history-of-3d-printing-when-was-3d-printing-invented/|title=History of 3D Printing: When Was 3D Printing Invented?|date=10 December 2018|website=All3DP|language=en|access-date=22 November 2019|archive-date=3 July 2019|archive-url=https://web.archive.org/web/20190703133203/https://all3dp.com/2/history-of-3d-printing-when-was-3d-printing-invented/|url-status=live}}</ref> later in 1987 or 1988.

The technology used by most 3D printers to date—especially hobbyist and consumer-oriented models—is [[fused deposition modeling]], a special application of plastic [[extrusion]], developed in 1988 by [[S. Scott Crump]] and commercialized by his company [[Stratasys]], which marketed its first FDM machine in 1992.<ref name=":4" />

Owning a 3D printer in the 1980s cost upwards of $300,000 ($650,000 in 2016 dollars).<ref>{{Cite web|date=2016-08-01|title=The Evolution of 3D Printing: Past, Present and Future|url=https://3dprintingindustry.com/news/evolution-3d-printing-past-present-future-90605/|access-date=2021-02-24|website=3D Printing Industry|language=en-US|archive-date=17 March 2021|archive-url=https://web.archive.org/web/20210317165528/https://3dprintingindustry.com/news/evolution-3d-printing-past-present-future-90605/|url-status=live}}</ref>

=== 1990s ===
AM processes for metal sintering or melting (such as [[selective laser sintering]], [[direct metal laser sintering]], and selective laser melting) usually went by their own individual names in the 1980s and 1990s. At the time, all metalworking was done by processes that are now called non-additive ([[casting]], [[metal fabrication|fabrication]], [[stamping (metalworking)|stamping]], and [[machining]]); although plenty of [[automation]] was applied to those technologies (such as by [[robot welding]] and [[numerical control|CNC]]), the idea of a tool or head moving through a 3D work envelope transforming a mass of [[raw material]] into a desired shape with a toolpath was associated in metalworking only with processes that removed metal (rather than adding it), such as CNC [[milling (machining)|milling]], CNC [[electrical discharge machining|EDM]], and many others. However, the automated techniques that ''added'' metal, which would later be called additive manufacturing, were beginning to challenge that assumption. By the mid-1990s, new techniques for material deposition were developed at [[Stanford]] and [[Carnegie Mellon University]], including microcasting<ref>{{cite journal|last1=Amon|first1=C. H.|last2=Beuth|first2=J. L.|last3=Weiss|first3=L. E.|last4=Merz|first4=R.|last5=Prinz|first5=F. B.|date=1998|title=Shape Deposition Manufacturing With Microcasting: Processing, Thermal and Mechanical Issues|url=http://repository.cmu.edu/cgi/viewcontent.cgi?article=1219&context=ece|format=PDF|journal=Journal of Manufacturing Science and Engineering|volume=120|issue=3|pages=656–665|doi=10.1115/1.2830171|access-date=20 December 2014|archive-url=https://web.archive.org/web/20141220122716/http://repository.cmu.edu/cgi/viewcontent.cgi?article=1219&context=ece|archive-date=20 December 2014|url-access=subscription}}</ref> and sprayed materials.<ref>{{cite journal|last1=Beck |first1=J.E. |last2=Fritz |first2=B. |last3=Siewiorek |first3=Daniel |last4=Weiss |first4=Lee |date=1992 |title=Manufacturing Mechatronics Using Thermal Spray Shape Deposition |url=http://utwired.engr.utexas.edu/lff/symposium/proceedingsarchive/pubs/manuscripts/1992/1992-31-beck.pdf |journal=Proceedings of the 1992 Solid Freeform Fabrication Symposium |access-date=20 December 2014 |archive-url=https://web.archive.org/web/20141224142429/http://utwired.engr.utexas.edu/lff/symposium/proceedingsarchive/pubs/manuscripts/1992/1992-31-beck.pdf |archive-date=24 December 2014 }}</ref> Sacrificial and support materials had also become more common, enabling new object geometries.<ref>{{cite conference|last1=Prinz|first1=F. B.|last2=Merz|first2=R.|last3=Weiss|first3=Lee|title=Building Parts You Could Not Build Before|conference=Proceedings of the 8th International Conference on Production Engineering|editor-last=Ikawa|editor-first=N.|publisher=Chapman & Hall|place=London, UK|date=1997|pages=40–44}}</ref>

The term ''3D printing'' originally referred to a powder bed process employing standard and custom [[inkjet]] print heads, developed at [[MIT]] by Emanuel Sachs in 1993 and commercialized by Soligen Technologies, Extrude Hone Corporation, and [[Z Corporation]].{{citation needed|date=October 2019}}

The year 1993 also saw the start of an inkjet 3D printer company initially named Sanders Prototype, Inc and later named [[Solidscape]], introducing a high-precision polymer jet fabrication system with soluble support structures, (categorized as a "dot-on-dot" technique).<ref name=":4" />

In 1995 the [[Fraunhofer Society]] developed the [[selective laser melting]] process.

=== 2000s ===
In the early 2000s 3D printers were still largely being used just in the manufacturing and research industries, as the technology was still relatively young and was too expensive for most consumers to be able to get their hands on. The 2000s was when larger scale use of the technology began being seen in industry, most often in the architecture and medical industries, though it was typically used for low accuracy modeling and testing, rather than the production of common manufactured goods or heavy prototyping.<ref>{{Cite journal |last1=Wu |first1=Peng |last2=Wang |first2=Jun |last3=Wang |first3=Xiangyu |date=2016-08-01 |title=A critical review of the use of 3-D printing in the construction industry |url=https://www.sciencedirect.com/science/article/pii/S0926580516300681 |journal=Automation in Construction |volume=68 |pages=21–31 |doi=10.1016/j.autcon.2016.04.005 |hdl=20.500.11937/7988 |s2cid=54037889 |issn=0926-5805|hdl-access=free }}</ref>

In 2005 users began to design and distribute plans for 3D printers that could print around 70% of their own parts, the original plans of which were designed by [[Adrian Bowyer]] at the University of Bath in 2004, with the name of the project being [[RepRap]] (Replicating Rapid-prototyper).<ref>{{Cite web |title=About - RepRap |url=https://reprap.org/wiki/About |access-date=2023-11-27 |website=reprap.org |language=en |archive-date=27 December 2023 |archive-url=https://web.archive.org/web/20231227010309/https://reprap.org/wiki/About |url-status=live }}</ref>

Similarly, in 2006 the Fab@Home project was started by Evan Malone and [[Hod Lipson]], another project whose purpose was to design a low-cost and open source fabrication system that users could develop on their own and post feedback on, making the project very collaborative.<ref>{{Cite journal |last1=Malone |first1=Evan |last2=Lipson |first2=Hod |date=2007-01-01 |title=Fab@Home: the personal desktop fabricator kit |journal=Rapid Prototyping Journal |volume=13 |issue=4 |pages=245–255 |doi=10.1108/13552540710776197 |issn=1355-2546}}</ref>

Much of the software for 3D printing available to the public at the time was [[Open-source software|open source]], and as such was quickly distributed and improved upon by many individual users. In 2009 the Fused Deposition Modeling (FDM) printing process patents expired. This opened the door to a new wave of startup companies, many of which were established by major contributors of these open source initiatives, with the goal of many of them being to start developing commercial FDM 3D printers that were more accessible to the general public.<ref>{{Cite book |chapter-url=https://ieeexplore.ieee.org/document/7273052 |access-date=2023-11-29 |doi=10.1109/PICMET.2015.7273052 |s2cid=10569154 |chapter=3D printing: On its historical evolution and the implications for business |title=2015 Portland International Conference on Management of Engineering and Technology (PICMET) |date=2015 |last1=Matias |first1=Elizabeth |last2=Rao |first2=Bharat |pages=551–558 |isbn=978-1-8908-4331-1 |archive-date=25 January 2024 |archive-url=https://web.archive.org/web/20240125024308/https://ieeexplore.ieee.org/document/7273052/ |url-status=live }}</ref>

=== 2010s ===
As the various additive processes matured, it became clear that soon metal removal would no longer be the only [[metalworking]] process done through a tool or head moving through a 3D work envelope, transforming a mass of raw material into a desired shape layer by layer. The 2010s were the first decade in which metal end-use parts such as engine brackets<ref name="GrabCAD_GE_bracket" /> and large nuts<ref name="AutoSQ-6" /> would be grown (either before or instead of machining) in [[job production]] rather than [[wikt:obligate#Adjective|obligately]] being machined from [[bar stock]] or plate. It is still the case that casting, fabrication, stamping, and machining are more prevalent than additive manufacturing in metalworking, but AM is now beginning to make significant inroads, and with the advantages of [[design for additive manufacturing]], it is clear to engineers that much more is to come.

One place that AM is making a significant inroad is in the aviation industry. With nearly 3.8 billion air travelers in 2016,<ref>{{Cite web|url=https://www.nationalgeographic.com/environment/article/air-travel-fuel-emissions-environment|title=As Billions More Fly, Here's How Aviation Could Evolve|date=22 June 2017|website=National Geographic|language=en-US|access-date=20 November 2020|archive-date=27 February 2021|archive-url=https://web.archive.org/web/20210227134029/https://www.nationalgeographic.com/environment/article/air-travel-fuel-emissions-environment|url-status=live}}</ref> the demand for fuel efficient and easily produced jet engines has never been higher. For large OEMs (original equipment manufacturers) like Pratt and Whitney (PW) and General Electric (GE) this means looking towards AM as a way to reduce cost, reduce the number of nonconforming parts, reduce weight in the engines to increase fuel efficiency and find new, highly complex shapes that would not be feasible with the antiquated manufacturing methods. One example of AM integration with aerospace was in 2016 when Airbus delivered the first of GE's [[CFM LEAP|LEAP]] engines. This engine has integrated 3D-printed fuel nozzles, reducing parts from 20 to 1, a 25% weight reduction, and reduced assembly times.<ref>{{Cite web|url=https://www.ge.com/additive/additive-manufacturing/industries/aviation-aerospace/|title=Aviation and Aerospace Industry|website=GE Additive|language=en-US|access-date=20 November 2020|archive-date=17 January 2021|archive-url=https://web.archive.org/web/20210117093806/https://www.ge.com/additive/additive-manufacturing/industries/aviation-aerospace|url-status=live}}</ref> A fuel nozzle is the perfect inroad for additive manufacturing in a jet engine since it allows for optimized design of the complex internals and it is a low-stress, non-rotating part. Similarly, in 2015, PW delivered their first AM parts in the PurePower PW1500G to Bombardier. Sticking to low-stress, non-rotating parts, PW selected the compressor stators and synch ring brackets<ref>{{Cite web|url=https://additivemanufacturing.com/2015/04/06/pratt-whitney-to-deliver-first-entry-into-service-engine-parts-using-additive-manufacturing/|title=Pratt & Whitney to Deliver First Entry Into Service Engine Parts Using Additive Manufacturing|date=6 April 2015|website=Additive Manufacturing|language=en-US|access-date=20 December 2020|archive-date=19 October 2020|archive-url=https://web.archive.org/web/20201019214011/http://additivemanufacturing.com/2015/04/06/pratt-whitney-to-deliver-first-entry-into-service-engine-parts-using-additive-manufacturing/|url-status=live}}</ref> to roll out this new manufacturing technology for the first time. While AM is still playing a small role in the total number of parts in the jet engine manufacturing process, the return on investment can already be seen by the reduction in parts, the rapid production capabilities and the "optimized design in terms of performance and cost".<ref>{{cite journal|last1=Han|first1=Pinlina|year=2017|title=Additive Design and Manufacturing of Jet Engine Parts|journal=Engineering|volume=3|issue=5|pages=648–652|doi=10.1016/j.eng.2017.05.017|doi-access=free|bibcode=2017Engin...3..648H }}</ref>

As technology matured, several authors began to speculate that 3D printing could aid in [[sustainable development]] in the developing world.<ref>{{cite journal|last2=r.Ishengoma|first2=Fredrick|year=2014|title=3D Printing: Developing Countries Perspectives|journal=International Journal of Computer Applications|volume=104|issue=11|page=30|bibcode=2014IJCA..104k..30R|doi=10.5120/18249-9329|last1=b. Mtaho|first1=Adam|arxiv=1410.5349|s2cid=5381455}}</ref>

In 2012, Filabot developed a system for closing the loop<ref>{{Cite web|url=https://www.miltonindependent.com/local-invention-excites-tech-world/|title=Filabot: Plastic Filament Maker|date=24 May 2012|website=Kickstarter|language=en-US|access-date=1 December 2018}}</ref> with plastic and allows for any FDM or FFF 3D printer to be able to print with a wider range of plastics.

In 2014, [[Benjamin S. Cook]] and Manos M. Tentzeris demonstrated the first multi-material, vertically integrated printed electronics additive manufacturing platform (VIPRE) which enabled 3D printing of functional electronics operating up to 40&nbsp;GHz.<ref>{{Cite web|url=https://smartech.gatech.edu/handle/1853/51844|title=VIPRE 3D Printed Electronics|date=26 March 2014|access-date=2 April 2019|language=en-US|last1=Cook|first1=Benjamin Stassen|archive-date=2 April 2019|archive-url=https://web.archive.org/web/20190402152732/https://smartech.gatech.edu/handle/1853/51844|url-status=live}}</ref>

As the price of printers started to drop people interested in this technology had more access and freedom to make what they wanted. As of 2014, the price for commercial printers was still high with the cost being over $2,000.<ref>{{Cite web|date=2017-06-22|title=3D Printer Price: How Much Does a 3D Printer Cost?|url=https://3dinsider.com/cost-of-3d-printer/|access-date=2021-02-24|website=3D Insider|language=en-US|archive-date=27 January 2021|archive-url=https://web.archive.org/web/20210127200154/https://3dinsider.com/cost-of-3d-printer/|url-status=live}}</ref>

The term "3D printing" originally referred to a process that deposits a binder material onto a powder bed with inkjet printer heads layer by layer. More recently, the popular vernacular has started using the term to encompass a wider variety of additive-manufacturing techniques such as electron-beam additive manufacturing and selective laser melting. The United States and global technical standards use the official term ''additive manufacturing'' for this broader sense.

The most commonly used 3D printing process (46% {{as of|2018|lc=on}}) is a material extrusion technique called [[Fused filament fabrication#Fused deposition modeling|fused deposition modeling]], or FDM.<ref name="statista1">{{Cite web|url= https://www.statista.com/statistics/560304/worldwide-survey-3d-printing-top-technologies/|title= Most used 3D printing technologies 2017–2018 {{!}} Statistic|website= Statista|language= en|access-date= 2 December 2018|archive-date= 2 March 2019|archive-url= https://web.archive.org/web/20190302150900/https://www.statista.com/statistics/560304/worldwide-survey-3d-printing-top-technologies/|url-status= live}}</ref> While FDM technology was invented after the other two most popular technologies, stereolithography (SLA) and selective laser sintering (SLS), FDM is typically the most inexpensive of the three by a large margin,{{citation needed|date=December 2020}} which lends to the popularity of the process.

=== 2020s ===
As of 2020, 3D printers have reached the level of quality and price that allows most people to enter the world of 3D printing. In 2020 decent quality printers can be found for less than US$200 for entry-level machines. These more affordable printers are usually [[fused deposition modeling]] (FDM) printers.<ref>{{Cite web|title=How Much Does a 3D Printer Cost? Calculate the ROI Now|url=https://formlabs.com/blog/how-to-calculate-3d-printer-cost/|access-date=2021-02-24|website=Formlabs|language=en-us|archive-date=16 January 2021|archive-url=https://web.archive.org/web/20210116003953/https://formlabs.com/blog/how-to-calculate-3d-printer-cost/|url-status=live}}</ref>

In November 2021 a British patient named Steve Verze received the world's first fully 3D-printed prosthetic eye from the [[Moorfields Eye Hospital]] in [[London]].<ref>{{Cite web|title=Patient receives the world's first fully 3D-printed prosthetic eye|url=https://www.engadget.com/patient-receives-a-fully-3-d-printed-eye-for-the-first-time-ever-142528877.html|access-date=2021-12-04|website=Engadget|date=30 November 2021|language=en-US|archive-date=4 December 2021|archive-url=https://web.archive.org/web/20211204001029/https://www.engadget.com/patient-receives-a-fully-3-d-printed-eye-for-the-first-time-ever-142528877.html|url-status=live}}</ref><ref>{{Cite web|title=Vsak dan prvi - 24ur.com|url=https://www.24ur.com/novice/znanost-in-tehnologija/britanec-prvi-clovek-na-svetu-s-3d-natisnjenim-ocesom.html|access-date=2021-12-04|website=www.24ur.com}}</ref>

In April 2024, the world's largest 3D printer, the Factory of the Future 1.0 was revealed at the [[University of Maine]]. It is able to make objects 96 feet long, or 29 meters.<ref>{{Cite web |title=World's biggest 3D printer whirs into action |url=https://www.bbc.com/news/articles/cx7d34nl5vwo |access-date=2024-04-26 |website=www.bbc.com |date=26 April 2024 |archive-date=26 April 2024 |archive-url=https://web.archive.org/web/20240426144711/https://www.bbc.com/news/articles/cx7d34nl5vwo |url-status=live }}</ref>

In 2024, researchers used [[machine learning]] to improve the construction of synthetic bone<ref>{{Cite web |last=University of Illinois at Urbana-Champaign |date=2024-05-25 |title=Synthetic Bones Designed by AI Set to Transform Orthopedic Surgery |url=https://scitechdaily.com/synthetic-bones-designed-by-ai-set-to-transform-orthopedic-surgery/ |access-date=2024-05-26 |website=SciTechDaily |language=en-US |archive-date=26 May 2024 |archive-url=https://web.archive.org/web/20240526170136/https://scitechdaily.com/synthetic-bones-designed-by-ai-set-to-transform-orthopedic-surgery/ |url-status=live }}</ref> and set a record for shock absorption.<ref>{{Cite web |last=Salas |first=Joe |date=2024-05-23 |title=Autonomous robot invents the world's best shock absorber |url=https://newatlas.com/technology/autonomous-ai-robot-building-crushing-breaks-record/ |access-date=2024-05-26 |website=New Atlas |language=en-US |archive-date=26 May 2024 |archive-url=https://web.archive.org/web/20240526170132/https://newatlas.com/technology/autonomous-ai-robot-building-crushing-breaks-record/ |url-status=live }}</ref>

In July 2024, researchers published a paper in ''Advanced Materials Technologies''  describing the development of artificial blood vessels using 3D-printing technology, which are as strong and durable as natural [[blood vessel]]s.<ref name=":1">{{Cite journal |last1=Fazal |first1=Faraz |last2=Melchels |first2=Ferry P.W. |last3=McCormack |first3=Andrew |last4=Silva |first4=Andreia F. |last5=Handley |first5=Ella-Louise |last6=Mazlan |first6=Nurul Ain |last7=Callanan |first7=Anthony |last8=Koutsos |first8=Vasileios |last9=Radacsi |first9=Norbert |date=2024-07-25 |title=Fabrication of a Compliant Vascular Graft Using Extrusion Printing and Electrospinning Technique |journal=Advanced Materials Technologies |volume=9 |issue=23 |language=en |doi=10.1002/admt.202400224 |issn=2365-709X|doi-access=free }}</ref> The process involved using a rotating spindle integrated into a 3D printer to create grafts from a water-based gel, which were then coated in biodegradable polyester molecules.<ref name=":1" />

== Benefits of 3D printing ==
Additive manufacturing or 3D printing has rapidly gained importance in the field of engineering due to its many benefits. The vision of 3D printing is design freedom, individualization,<ref>{{Cite journal |last1=Weller |first1=Christian |last2=Kleer |first2=Robin |last3=Piller |first3=Frank T. |date=2015-06-01 |title=Economic implications of 3D printing: Market structure models in light of additive manufacturing revisited |url=https://www.sciencedirect.com/science/article/pii/S0925527315000547 |journal=International Journal of Production Economics |volume=164 |pages=43–56 |doi=10.1016/j.ijpe.2015.02.020 |issn=0925-5273 |access-date=27 March 2024 |archive-date=9 July 2019 |archive-url=https://web.archive.org/web/20190709032946/https://www.sciencedirect.com/science/article/pii/S0925527315000547 |url-status=live |url-access=subscription }}</ref> decentralization<ref>{{Cite journal |last1=Ben-Ner |first1=Avner |last2=Siemsen |first2=Enno |date=February 2017 |title=Decentralization and Localization of Production: The Organizational and Economic Consequences of Additive Manufacturing (3D Printing) |url=http://journals.sagepub.com/doi/10.1177/0008125617695284 |journal=California Management Review |language=en |volume=59 |issue=2 |pages=5–23 |doi=10.1177/0008125617695284 |issn=0008-1256 |access-date=27 March 2024 |archive-date=27 March 2024 |archive-url=https://web.archive.org/web/20240327075657/https://journals.sagepub.com/doi/10.1177/0008125617695284 |url-status=live |url-access=subscription }}</ref> and executing processes that were previously impossible through alternative methods.<ref>{{Cite journal |last1=Li |first1=Zhaolong |last2=Wang |first2=Qinghai |last3=Liu |first3=Guangdong |date=April 2022 |title=A Review of 3D Printed Bone Implants |journal=Micromachines |language=en |volume=13 |issue=4 |pages=528 |doi=10.3390/mi13040528 |doi-access=free |pmid=35457833 |pmc=9025296 |issn=2072-666X}}</ref> Some of these benefits include enabling faster prototyping, reducing manufacturing costs, increasing product customization, and improving product quality.<ref>P. Sivasankaran and B. Radjaram, "3D Printing and Its Importance in Engineering - A Review", 2020 International Conference on System, Computation, Automation and Networking (ICSCAN), Pondicherry, India, 2020, pp. 1-3, {{doi|10.1109/ICSCAN49426.2020.9262378}}.</ref>

Furthermore, the capabilities of 3D printing have extended beyond traditional manufacturing, like lightweight construction,<ref>{{Cite journal |last1=Zhang |first1=Zhi |last2=Zhang |first2=Lei |last3=Song |first3=Bo |last4=Yao |first4=Yonggang |last5=Shi |first5=Yusheng |date=2022-03-01 |title=Bamboo-inspired, simulation-guided design and 3D printing of light-weight and high-strength mechanical metamaterials |url=https://www.sciencedirect.com/science/article/pii/S2352940721003310 |journal=Applied Materials Today |volume=26 |pages=101268 |doi=10.1016/j.apmt.2021.101268 |issn=2352-9407|url-access=subscription }}</ref> or repair and maintenance<ref>{{Cite journal |last1=Westerweel |first1=Bram |last2=Basten |first2=Rob |last3=denBoer |first3=Jelmar |last4=vanHoutum |first4=Geert-Jan |date=June 2021 |title=Printing Spare Parts at Remote Locations: Fulfilling the Promise of Additive Manufacturing |url=https://journals.sagepub.com/doi/10.1111/poms.13298 |journal=Production and Operations Management |language=en |volume=30 |issue=6 |pages=1615–1632 |doi=10.1111/poms.13298 |issn=1059-1478 |access-date=27 March 2024 |archive-date=27 March 2024 |archive-url=https://web.archive.org/web/20240327075657/https://journals.sagepub.com/doi/10.1111/poms.13298 |url-status=live }}</ref> with applications in prosthetics,<ref>{{Cite journal |last1=Manero |first1=Albert |last2=Smith |first2=Peter |last3=Sparkman |first3=John |last4=Dombrowski |first4=Matt |last5=Courbin |first5=Dominique |last6=Kester |first6=Anna |last7=Womack |first7=Isaac |last8=Chi |first8=Albert |date=January 2019 |title=Implementation of 3D Printing Technology in the Field of Prosthetics: Past, Present, and Future |journal=International Journal of Environmental Research and Public Health |language=en |volume=16 |issue=9 |pages=1641 |doi=10.3390/ijerph16091641 |doi-access=free |pmid=31083479 |pmc=6540178 |issn=1660-4601}}</ref> bioprinting,<ref>{{Cite journal |last1=Caprioli |first1=Matteo |last2=Roppolo |first2=Ignazio |last3=Chiappone |first3=Annalisa |last4=Larush |first4=Liraz |last5=Pirri |first5=Candido Fabrizio |last6=Magdassi |first6=Shlomo |date=2021-04-28 |title=3D-printed self-healing hydrogels via Digital Light Processing |journal=Nature Communications |language=en |volume=12 |issue=1 |pages=2462 |doi=10.1038/s41467-021-22802-z |pmid=33911075 |bibcode=2021NatCo..12.2462C |issn=2041-1723|pmc=8080574 }}</ref> food industry,<ref>{{Cite journal |last1=Nachal |first1=N. |last2=Moses |first2=J. A. |last3=Karthik |first3=P. |last4=Anandharamakrishnan |first4=C. |date=2019-09-01 |title=Applications of 3D Printing in Food Processing |journal=Food Engineering Reviews |language=en |volume=11 |issue=3 |pages=123–141 |doi=10.1007/s12393-019-09199-8 |issn=1866-7929}}</ref> rocket building,<ref>{{Cite journal |last=Zastrow |first=Mark |date=2020-02-05 |title=3D printing gets bigger, faster and stronger |url=https://www.nature.com/articles/d41586-020-00271-6 |journal=Nature |language=En |volume=578 |issue=7793 |pages=20–23 |doi=10.1038/d41586-020-00271-6 |pmid=32025009 |bibcode=2020Natur.578...20Z |issn=0028-0836}}</ref> design and art<ref>{{Cite journal |last1=Schubert |first1=Carl |last2=Langeveld |first2=Mark C. van |last3=Donoso |first3=Larry A. |date=2014-02-01 |title=Innovations in 3D printing: a 3D overview from optics to organs |url=https://bjo.bmj.com/content/98/2/159 |journal=British Journal of Ophthalmology |language=en |volume=98 |issue=2 |pages=159–161 |doi=10.1136/bjophthalmol-2013-304446 |issn=0007-1161 |pmid=24288392 |access-date=27 March 2024 |archive-date=27 March 2024 |archive-url=https://web.archive.org/web/20240327081159/https://bjo.bmj.com/content/98/2/159 |url-status=live }}</ref> and renewable energy systems.<ref>K. J. A. Al Ahbabi, M. M. S. Alrashdi and W. K. Ahmed, "The Capabilities of 3D Printing Technology in the Production of Battery Energy Storage System", 2021 6th International Conference on Renewable Energy: Generation and Applications (ICREGA), Al Ain, United Arab Emirates, 2021, pp. 211–216, {{doi|10.1109/ICREGA50506.2021.9388302}}.</ref> 3D printing technology can be used to produce battery energy storage systems, which are essential for sustainable energy generation and distribution.

Another benefit of 3D printing is the technology's ability to produce complex geometries with high precision and accuracy.<ref>F. Auricchio, "The magic world of 3D printing", 2017 IEEE MTT-S International Microwave Workshop Series on Advanced Materials and Processes for RF and THz Applications (IMWS-AMP), Pavia, Italy, 2017, pp. 1-1, {{doi|10.1109/IMWS-AMP.2017.8247328}}.</ref> This is particularly relevant in the field of microwave engineering, where 3D printing can be used to produce components with unique properties that are difficult to achieve using traditional manufacturing methods.<ref>{{cite journal |last1=Attaran |first1=Mohsen |title=The rise of 3-D printing: The advantages of additive manufacturing over traditional manufacturing |journal=Business Horizons |date=2017 |volume=60 |issue=5 |pages=677–688 |doi=10.1016/j.bushor.2017.05.011}}</ref>

Additive Manufacturing processes generate minimal waste by adding material only where needed, unlike traditional methods that cut away excess material.<ref>{{cite journal |last1=Javaid |first1=Mohd |last2=Haleem |first2=Abid |year=2021 |title=Role of additive manufacturing applications towards environmental sustainability |journal=Advanced Industrial and Engineering Polymer Research |volume=4 |issue=4 |pages=312–322 |doi=10.1016/j.aiepr.2021.07.005 |doi-access=free}}</ref> This reduces both material costs and environmental impact.<ref>{{cite web |url=https://www.samaterials.com/additive-manufacturing-vs-traditional-manufacturing.html |title=Additive Manufacturing vs Traditional Manufacturing |last=Trento |first=Chin |website=Stanford Advanced Materials |date=Dec 27, 2023 |access-date=July 31, 2024}}</ref> This reduction in waste also lowers energy consumption for material production and disposal, contributing to a smaller [[carbon footprint]].<ref>{{cite journal |last1=Elbadawi |first1=Moe |last2=Basit |first2=A.W. |year=2023 |title=Energy consumption and carbon footprint of 3D printing in pharmaceutical manufacture |journal=International Journal of Pharmaceutics |volume=639 |doi=10.1016/j.ijpharm.2023.122926 |doi-access=free|pmid=37030639 }}</ref><ref>{{cite journal |last1=Hegab |first1=Hussain |last2=Khanna |first2=Navneet |year=2023 |title=Design for sustainable additive manufacturing: A review |journal=Sustainable Materials and Technologies |volume=35 |page=e00576 |doi=10.1016/j.susmat.2023.e00576|bibcode=2023SusMT..3500576H }}</ref>

== General principles ==

=== Modeling ===
{{main|3D modeling}}
[[File:84530877 FillingSys (9415669149).jpg|thumb|[[CAD]] model used for 3D printing]]
[[File:Doob NY SOHO 3D selfie photo booth IMG 4939 FRD.jpg|thumb|upright|3D models can be generated from 2D pictures taken at a 3D photo booth.]]

3D printable models may be created with a [[computer-aided design]] (CAD) package, via a [[3D scanner#Hand-held laser scanners|3D scanner]], or by a plain [[digital camera]] and [[photogrammetry software]]. 3D printed models created with CAD result in relatively fewer errors than other methods. Errors in 3D printable models can be identified and corrected before printing.<ref name="Jacobs">{{Cite book|title=Rapid Prototyping & Manufacturing: Fundamentals of Stereolithography|url={{google books |plainurl=y |id=HvcN0w1VyxwC}}|publisher=Society of Manufacturing Engineers|date=1 January 1992|isbn=978-0-87263-425-1|first=Paul Francis|last=Jacobs}}</ref> The manual modeling process of preparing geometric data for 3D computer graphics is similar to plastic arts such as sculpting. 3D scanning is a process of collecting digital data on the shape and appearance of a real object, and creating a digital model based on it.

CAD models can be saved in the [[STL (file format)|stereolithography file format (STL)]], a de facto CAD file format for additive manufacturing that stores data based on triangulations of the surface of CAD models. STL is not tailored for additive manufacturing because it generates large file sizes of topology-optimized parts and lattice structures due to the large number of surfaces involved. A newer CAD file format, the [[Additive manufacturing file format|additive manufacturing file format (AMF)]], was introduced in 2011 to solve this problem. It stores information using curved triangulations.<ref>{{Cite journal|last1=Azman|first1=Abdul Hadi|last2=Vignat|first2=Frédéric|last3=Villeneuve|first3=François|date=29 April 2018|journal=Jurnal Teknologi|language=en|volume=80|issue=4|issn=2180-3722|doi=10.11113/jt.v80.12058|title=Cad Tools and File Format Performance Evaluation in Designing Lattice Structures for Additive Manufacturing|doi-access=free}}</ref>

=== Printing ===

Before printing a 3D model from an [[STL (file format)|STL]] file, it must first be examined for errors. Most [[Computer-aided design|CAD]] applications produce errors in output STL files,<ref>{{cite web |url=http://print.limitstate.com/ |title=3D solid repair software – Fix STL polygon mesh files – LimitState:FIX |publisher=Print.limitstate.com |access-date=4 January 2016 |archive-date=4 March 2016 |archive-url=https://web.archive.org/web/20160304080143/http://print.limitstate.com/ |url-status=live }}</ref><ref>{{cite web |url=http://www.yellowgurl.com/best-3d-pens-reviews/ |title=3D Printing Pens |publisher=yellowgurl.com |access-date=9 August 2016 |archive-url=https://web.archive.org/web/20160916124703/http://www.yellowgurl.com/best-3d-pens-reviews/ |archive-date=16 September 2016 }}</ref> of the following types:
* holes
* faces normals
* self-intersections
* noise shells
* manifold errors<ref>{{cite web |url=https://modelrepair.azurewebsites.net/ |title=Model Repair Service |publisher=Modelrepair.azurewebsites.net |access-date=4 January 2016 |archive-date=4 March 2016 |archive-url=https://web.archive.org/web/20160304053710/https://modelrepair.azurewebsites.net/ }}</ref>
* overhang issues<ref>{{Cite web|date=2021-06-16|title=3D Printing Overhang: How to 3D Print Overhangs|url=https://all3dp.com/2/3d-printing-overhang-how-to-master-overhangs-exceeding-45/|access-date=2021-10-11|website=All3DP|language=en|archive-date=9 October 2021|archive-url=https://web.archive.org/web/20211009144332/https://all3dp.com/2/3d-printing-overhang-how-to-master-overhangs-exceeding-45/|url-status=live}}</ref>

A step in the STL generation known as "repair" fixes such problems in the original model.<ref>{{cite web |url=http://software.materialise.com/magics |title=Magics, the Most Powerful 3D Printing Software {{pipe}} Software for additive manufacturing |publisher=Software.materialise.com |access-date=4 January 2016 |archive-date=4 January 2016 |archive-url=https://web.archive.org/web/20160104021505/http://software.materialise.com/magics |url-status=live }}</ref><ref>{{cite web |url=http://www.netfabb.com/netfabbcloud.php |title=netfabb Cloud Services |publisher=Netfabb.com |date=15 May 2009 |access-date=4 January 2016 |archive-date=30 December 2015 |archive-url=https://web.archive.org/web/20151230161032/http://www.netfabb.com/netfabbcloud.php }}</ref> Generally, STLs that have been produced from a model obtained through [[3D scanner|3D scanning]] often have more of these errors<ref>{{cite web |url=http://anamarva.com/how-to-repair-a-3d-scan-for-printing/ |title=How to repair a 3D scan for printing |publisher=Anamarva.com |access-date=4 January 2016 |archive-date=24 January 2016 |archive-url=https://web.archive.org/web/20160124034125/http://anamarva.com/how-to-repair-a-3d-scan-for-printing/ |url-status=live }}</ref> as 3D scanning is often achieved by point to point acquisition/mapping. [[3D reconstruction]] often includes errors.<ref>{{cite journal |author=Fausto Bernardini, [[Holly Rushmeier|Holly E. Rushmeier]] |title=The 3D Model Acquisition Pipeline GAS |journal=Computer Graphics Forum |volume=21 |issue=2 |pages=149–72 |year=2002 |url=http://www1.cs.columbia.edu/~allen/PHOTOPAPERS/pipeline.fausto.pdf |doi=10.1111/1467-8659.00574 |s2cid=15779281 |access-date=4 January 2016 |archive-date=3 March 2016 |archive-url=https://web.archive.org/web/20160303225607/http://www1.cs.columbia.edu/~allen/PHOTOPAPERS/pipeline.fausto.pdf |url-status=live }}</ref>

Once completed, the STL file needs to be processed by a piece of software called a "[[Slicer (3D printing)|slicer]]", which converts the model into a series of thin layers and produces a [[G-code]] file containing instructions tailored to a specific type of 3D printer ([[Fused deposition modeling|FDM printers]]).<ref name="Satyanarayana" /> This G-code file can then be printed with 3D printing client software (which loads the G-code and uses it to instruct the 3D printer during the 3D printing process).

Printer resolution describes layer thickness and X–Y resolution in [[dots per inch]] (dpi) or [[micrometre|micrometer]]s (μm). Typical layer thickness is around {{convert|100|pitch|dpi|lk=on}}, although some machines can print layers as thin as {{convert|16|pitch|dpi}}.<ref name="Auto3D-17" /> X–Y resolution is comparable to that of [[laser printer]]s. The particles (3D dots) are around {{convert|0.01|to|0.1|pitch|dpi}} in diameter.<ref>{{cite journal| last1=Lee | first1=Handol | last2=Kwak | first2=Dong-Bin | last3=Choi | first3=Chi Young | last4=Ahn | first4=Kang-Ho |title=Accurate measurements of particle emissions from a three-dimensional printer using a chamber test with a mixer-installed sampling system|journal=Scientific Reports|volume=13|id=6495|year=2023| issue=1 | page=6495 | doi=10.1038/s41598-023-33538-9 | pmid=37081153 | pmc=10119104 | bibcode=2023NatSR..13.6495L |doi-access=free}}</ref> For that printer resolution, specifying a mesh resolution of {{nowrap|0.01–0.03 mm}} and a chord length {{nowrap|≤ 0.016 mm}} generates an optimal STL output file for a given model input file.<ref>{{Cite web|url=https://cdn2.hubspot.net/hubfs/340051/Design_Guides/Xometry_DesignGuide_3DPrinting.pdf?submissionGuid=d1681094-eb0b-46c0-9e8a-b265cf26f5be|title=Design Guide: Preparing a File for 3D Printing|website=Xometry|access-date=19 January 2018|archive-date=20 January 2018|archive-url=https://web.archive.org/web/20180120065842/https://cdn2.hubspot.net/hubfs/340051/Design_Guides/Xometry_DesignGuide_3DPrinting.pdf?submissionGuid=d1681094-eb0b-46c0-9e8a-b265cf26f5be|url-status=live}}</ref> Specifying higher resolution results in larger files without increase in print quality.

[[File:Hyperboloid Print.ogv|thumb|3:30 timelapse of an 80-minute video of an object being made out of [[Polylactic acid|PLA]] using molten polymer deposition]]
Construction of a model with contemporary methods can take anywhere from several hours to several days, depending on the method used and the size and complexity of the model. Additive systems can typically reduce this time to a few hours, although it varies widely depending on the type of machine used and the size and number of models being produced simultaneously.

=== Finishing ===

Though the printer-produced resolution and surface finish are sufficient for some applications, post-processing and finishing methods allow for benefits such as greater dimensional accuracy, smoother surfaces, and other modifications such as coloration.

The surface finish of a 3D-printed part can improved using subtractive methods such as sanding and bead blasting. When smoothing parts that require dimensional accuracy, it is important to take into account the volume of the material being removed.<ref name="smooth"/>

Some printable polymers, such as [[acrylonitrile butadiene styrene]] (ABS), allow the surface finish to be smoothed and improved using chemical vapor processes<ref>{{cite web|last1=Kraft|first1=Caleb|title=Smoothing Out Your 3D Prints With Acetone Vapor|url=http://makezine.com/2014/09/24/smoothing-out-your-3d-prints-with-acetone-vapor/|website=Make|access-date=5 January 2016|archive-date=24 March 2016|archive-url=https://web.archive.org/web/20160324154754/http://makezine.com/2014/09/24/smoothing-out-your-3d-prints-with-acetone-vapor/|url-status=live}}</ref> based on [[acetone]] or similar solvents.

Some additive manufacturing techniques can benefit from [[Annealing (materials science)|annealing]] as a post-processing step. Annealing a 3D-printed part allows for better internal layer bonding due to recrystallization of the part. It allows for an increase in mechanical properties, some of which are [[fracture toughness]],<ref>{{cite journal |doi=10.1016/j.polymer.2018.04.024 |title=Increased fracture toughness of additively manufactured amorphous thermoplastics via thermal annealing |journal=Polymer |volume=144 |pages=192–204 |year=2018 |issn=0032-3861 |last1=Hart |first1=Kevin R. |last2=Dunn |first2=Ryan M. |last3=Sietins |first3=Jennifer M. |last4=Hofmeister Mock |first4=Clara M. |last5=Mackay |first5=Michael E. |last6=Wetzel |first6=Eric D. |doi-access=free }}</ref> [[flexural strength]],<ref>{{cite journal |last1=Valvez |first1=S. |last2=Silva |first2=A.P. |last3=Reis |first3=P.N.B. |last4=Berto |first4=F. |title=Annealing effect on mechanical properties of 3D printed composites |journal=Procedia Structural Integrity |volume=37 |pages=738–745 |year=2022 |issn=2452-3216 |doi=10.1016/j.prostr.2022.02.004 |doi-access=free }}</ref> [[impact resistance]],<ref name="benwood-anneal">{{cite journal |last1=Benwood |first1=C. |last2=Anstey |first2=A. |last3=Andrzejewski |first3=J. |last4=Misra |first4=M. |last5=Mohanty |first5=A. K. |title=Improving the Impact Strength and Heat Resistance of 3D Printed Models: Structure, Property, and Processing Correlationships during Fused Deposition Modeling (FDM) of Poly(Lactic Acid) |journal=ACS Omega |volume=3 |issue=4 |pages=4400–4411 |year=2018 |doi=10.1021/acsomega.8b00129 |pmid=31458666 |pmc=6641607}}</ref> and [[heat resistance]].<ref name="benwood-anneal" /> Annealing a component may not be suitable for applications where dimensional accuracy is required, as it can introduce warpage or shrinkage due to heating and cooling.<ref>{{cite journal | doi=10.1108/RPJ-04-2021-0090 | title=The effect of annealing on deformation and mechanical strength of tough PLA and its application in 3D printed prosthetic sockets | journal=Rapid Prototyping Journal | volume=27 | issue=11 | pages=81–89 | year=2021 | last1=Wijnbergen | first1=D.C. | last2=van der Stelt | first2=M. | last3=Verhamme | first3=L.M. | s2cid=244259184 | doi-access=free }}</ref>

Additive or subtractive hybrid manufacturing (ASHM) is a method that involves producing a 3D printed part and using [[machining]] (subtractive manufacturing) to remove material.<ref>{{cite journal |doi=10.1016/j.promfg.2016.08.067 |title=A Novel Method for Additive/Subtractive Hybrid Manufacturing of Metallic Parts |journal=Procedia Manufacturing |volume=5 |pages=1018–1030 |year=2016 |issn=2351-9789 |author1=Wei Du |author2=Qian Bai |author3=Bi Zhang |doi-access=free }}</ref> Machining operations can be completed after each layer, or after the entire 3D print has been completed depending on the application requirements. These hybrid methods allow for 3D-printed parts to achieve better surface finishes and dimensional accuracy.<ref>{{cite book |title=Transactions on Intelligent Welding Manufacturing |editor1-first=S. |editor1-last=Chen |editor2-first=Y. |editor2-last=Zhang |editor3-first=Z. |editor3-last=Feng |chapter=Investigation on Surface Quality in a Hybrid Manufacturing System Combining Wire and Arc Additive Manufacturing and Machining |vauthors=Li F, Chen S, Shi J, Tian H |publisher=Springer |year=2018 |pages=127–137 |doi=10.1007/978-981-10-7043-3_9 |isbn=978-981-10-7042-6 }}</ref>

The layered structure of traditional additive manufacturing processes leads to a stair-stepping effect on part-surfaces that are curved or tilted with respect to the building platform. The effect strongly depends on the layer height used, as well as the orientation of a part surface inside the building process.<ref>{{Cite journal|last1=Delfs|first1=P.|last2=T̈ows|first2=M.|last3=Schmid|first3=H.-J.|date=October 2016|title=Optimized build orientation of additive manufactured parts for improved surface quality and build time|journal=Additive Manufacturing|volume=12|pages=314–320|doi=10.1016/j.addma.2016.06.003|issn=2214-8604}}</ref> This effect can be minimized using "variable layer heights" or "adaptive layer heights". These methods decrease the layer height in places where higher quality is needed.<ref>{{cite web |url=https://all3dp.com/2/cura-adaptive-layers-simply-explained/ |title=Cura Adaptive Layers – Simply Explained |last=O'Connell |first=Jackson |website=All3DP |date=April 29, 2022 |access-date=March 29, 2023 |archive-date=29 March 2023 |archive-url=https://web.archive.org/web/20230329190921/https://all3dp.com/2/cura-adaptive-layers-simply-explained/ |url-status=live }}</ref>

Painting a 3D-printed part offers a range of finishes and appearances that may not be achievable through most 3D printing techniques. The process typically involves several steps, such as surface preparation, [[Primer (paint)|priming]], and painting.<ref>{{cite web |last=Boissonneault |first=Tess |title=Your Guide to Painting PLA 3D Prints |url=https://www.wevolver.com/article/your-guide-to-painting-pla-3d-prints |website=Wevolver |date=15 Aug 2022 |access-date=March 29, 2023 |archive-date=29 March 2023 |archive-url=https://web.archive.org/web/20230329190909/https://www.wevolver.com/article/your-guide-to-painting-pla-3d-prints |url-status=live }}</ref> These steps help prepare the surface of the part and ensuring the paint adheres properly.

Some additive manufacturing techniques are capable of using multiple materials simultaneously. These techniques are able to print in multiple colors and color combinations simultaneously and can produce parts that may not necessarily require painting.

Some printing techniques require internal supports to be built to support overhanging features during construction. These supports must be mechanically removed or dissolved if using a water-soluble support material such as [[Polyvinyl alcohol|PVA]] after completing a print.

Some commercial metal 3D printers involve cutting the metal component off the metal substrate after deposition. A new process for the [[GMAW]] 3D printing allows for substrate surface modifications to remove [[aluminium]]<ref>{{cite journal |doi=10.1089/3dp.2014.0015 |title=Substrate Release Mechanisms for Gas Metal Arc Weld 3D Aluminum Metal Printing |journal=3D Printing and Additive Manufacturing |volume=1 |issue=4 |page=204 |year=2014 |last1=Haselhuhn |first1=Amberlee S. |last2=Gooding |first2=Eli J. |last3=Glover |first3=Alexandra G. |last4=Anzalone |first4=Gerald C. |last5=Wijnen |first5=Bas |last6=Sanders |first6=Paul G. |last7=Pearce |first7=Joshua M. |s2cid=135499443 }}</ref> or [[steel]].<ref>{{cite journal |doi=10.1016/j.jmatprotec.2015.06.038 |title=In situ formation of substrate release mechanisms for gas metal arc weld metal 3-D printing |journal=Journal of Materials Processing Technology |volume=226 |page=50 |year=2015 |last1=Haselhuhn |first1=Amberlee S. |last2=Wijnen |first2=Bas |last3=Anzalone |first3=Gerald C. |last4=Sanders |first4=Paul G. |last5=Pearce |first5=Joshua M. |url=https://digitalcommons.mtu.edu/cgi/viewcontent.cgi?article=1056&context=materials_fp |access-date=19 July 2019 |archive-date=28 April 2019 |archive-url=https://web.archive.org/web/20190428152430/https://digitalcommons.mtu.edu/cgi/viewcontent.cgi?article=1056&context=materials_fp |url-status=live }}</ref>

=== Materials ===
[[image:Stoofbrug Amsterdam detail 1.jpg|thumb|Detail of the {{Ill|Stoofbrug|nl}} in Amsterdam, the world's first 3D-printed metal bridge<ref name="euronews.com">{{Cite web|url=https://www.euronews.com/next/2021/07/16/the-world-s-first-3d-printed-steel-bridge-has-opened-in-amsterdam|title=Amsterdam unveils the world's first 3D-printed steel bridge|first=Natalie|last=Huet|date=16 July 2021|website=euronews}}</ref>]]

Traditionally, 3D printing focused on [[polymers]] for printing, due to the ease of manufacturing and handling polymeric materials. However, the method has rapidly evolved to not only print various polymers<ref>{{cite journal |doi=10.1016/j.compositesb.2016.11.034 |title=3D printing of polymer matrix composites: A review and prospective |journal=Composites Part B: Engineering |volume=110 |pages=442–458 |year=2017 |last1=Wang |first1=Xin  |last2=Jiang |first2=Man |last3=Zhou |first3=Zuowan |last4=Gou |first4=Jihua |last5=Hui |first5=David }}</ref> but also metals,<ref>{{Cite thesis |title=On the degradation of porous stainless steel |first=L. |last=Rose |pages=104–143 |year=2011 |doi=10.14288/1.0071732 |publisher=University of British Columbia }}</ref><ref>{{cite journal |doi=10.1088/1757-899X/285/1/012028 |title=Additive manufacturing for steels: a review |journal=IOP Conference Series: Materials Science and Engineering |volume=285 |issue=1 |page=012028 |year=2018 |last1=Zadi-Maad |first1=Ahmad |last2=Rohbib |first2=Rohbib  |last3=Irawan |first3=A |url=https://www.researchgate.net/publication/322816447|bibcode=2018MS&E..285a2028Z |doi-access=free }}</ref> chocolates,<ref>{{Cite web |last=Hollister |first=Sean |date=2024-02-17 |title=I printed chocolate on a 3D printer and ate it |url=https://www.theverge.com/2024/2/17/24074150/cocoa-press-3d-printed-chocolate |access-date=2025-06-22 |website=The Verge |language=en-US}}</ref> and [[ceramics]],<ref>{{cite journal |doi=10.1016/j.dental.2019.02.026 |pmid=30948230 |title=Additive manufacturing of ceramics for dental applications |journal=Dental Materials |volume=35 |issue=6 |pages=825–846 |year=2019 |last1=Galante |first1=Raquel |last2=G. Figueiredo-Pina |first2=Celio  |last3=Serro |first3=Ana Paula |s2cid=96434269 }}</ref> making 3D printing a versatile option for manufacturing. Layer-by-layer fabrication of three-dimensional physical models is a modern concept that "stems from the ever-growing CAD industry, more specifically the solid modeling side of CAD. Before solid modeling was introduced in the late 1980s, three-dimensional models were created with wire frames and surfaces."<ref>{{Cite book|last1=Cooper |first1=Kenneth G.|title=Rapid prototyping technology: selection and application|date=2001|publisher=Marcel Dekker|isbn=0-8247-0261-1|location=New York|pages=39–41|oclc=45873626}}</ref> but in all cases the layers of materials are controlled by the printer and the material properties. The three-dimensional material layer is controlled by the deposition rate as set by the printer operator and stored in a computer file. The earliest printed patented material was a hot melt type ink for printing patterns using a heated metal alloy.

Charles Hull filed the first patent on August 8, 1984, to use a UV-cured acrylic resin using a UV-masked light source at UVP Corp to build a simple model. The SLA-1 was the first SL product announced by 3D Systems at Autofact Exposition, Detroit, November 1978. The SLA-1 Beta shipped in Jan 1988 to Baxter Healthcare, Pratt and Whitney, General Motors and AMP. The first production SLA-1 shipped to Precision Castparts in April 1988. The UV resin material changed over quickly to an epoxy-based material resin. In both cases, SLA-1 models needed UV oven curing after being rinsed in a solvent cleaner to remove uncured boundary resin. A post cure apparatus (PCA) was sold with all systems. The early resin printers required a blade to move fresh resin over the model on each layer. The layer thickness was 0.006 inches and the HeCd laser model of the SLA-1 was 12 watts and swept across the surface at 30 in per second. UVP was acquired by 3D Systems in January 1990.<ref name=":0">{{Cite book|last=Burns|first=Marshall|title=Automated fabrication: improving productivity in manufacturing|date=1993|publisher=PTR Prentice Hall|isbn=0-13-119462-3|location=Englewood Cliffs, N.J.|pages=8, 15, 49, 95, 97|oclc=27810960}}</ref>

A review of the history shows that a number of materials (resins, plastic powder, plastic filament and hot-melt plastic ink) were used in the 1980s for patents in the rapid prototyping field. Masked lamp UV-cured resin was also introduced by Cubital's Itzchak Pomerantz in the Soldier 5600, Carl Deckard's (DTM) laser sintered thermoplastic powders, and adhesive-laser cut paper (LOM) stacked to form objects by Michael Feygin before 3D Systems made its first announcement. Scott Crump was also working with extruded "melted" plastic filament modeling (FDM) and drop deposition had been patented by William E Masters a week after Hull's patent in 1984, but he had to discover thermoplastic inkjets, introduced by Visual Impact Corporation 3D printer in 1992, using inkjets from Howtek, Inc., before he formed BPM to bring out his own 3D printer product in 1994.<ref name=":0" />

The most common polymers for personal 3D printers are [[polylactic acid]] (PLA) and [[PETG]].

=== Multi-material 3D printing ===
{{main|Multi-material 3D printing}}
[[File:3DBenchy created using color mixing on an FDM printer.jpg|thumb|A multi-material [[3DBenchy]]]]

Efforts to achieve multi-material 3D printing range from enhanced FDM-like processes like VoxelJet to novel voxel-based printing technologies like layered assembly.<ref>{{cite journal |doi=10.1016/j.addma.2019.03.032 |title=Parallel electrostatic grippers for layered assembly |year=2019 |last1=Mici |first1=Joni |last2=Ko |first2=Jang Won |last3=West |first3=Jared |last4=Jaquith |first4=Jeffrey |last5=Lipson |first5=Hod |journal=Additive Manufacturing |volume=27 |pages=451–460 |s2cid=141154762}}</ref>

A drawback of many existing 3D printing technologies is that they only allow one material to be printed at a time, limiting many potential applications that require the integration of different materials in the same object. Multi-material 3D printing solves this problem by allowing objects of complex and heterogeneous arrangements of materials to be manufactured using a single printer. Here, a material must be specified for each [[voxel]] (or 3D printing pixel element) inside the final object volume.

The process can be fraught with complications, however, due to the isolated and monolithic algorithms. Some commercial devices have sought to solve these issues, such as building a Spec2Fab translator, but the progress is still very limited.<ref name="source">{{cite conference |title=Spec2Fab: A reducer-tuner model for translating specifications to 3D prints |language= en |conference=Spec2Fab |citeseerx=10.1.1.396.2985 }}</ref> Nonetheless, in the medical industry, a concept of 3D-printed pills and vaccines has been presented.<ref name="source6">{{cite conference |title=Researchers Turn to Multi-Material 3D Printing to Develop Responsive, Versatile Smart Composites |language=en |url=https://3dprint.com/191717/sequential-cell-opening-mechanism/  |access-date=19 February 2019 |archive-date=20 February 2019 |archive-url=https://web.archive.org/web/20190220063028/https://3dprint.com/191717/sequential-cell-opening-mechanism/ |url-status=live }}</ref>
With this new concept, multiple medications can be combined, which is expected to decrease many risks. With more and more applications of multi-material 3D printing, the costs of daily life and high technology development will become inevitably lower.

Metallographic materials of 3D printing is also being researched.<ref name="source001">{{cite conference |title= CIMP-3D |language= zh |url= http://www.51shape.com/?p=10586  |access-date= 19 February 2019 |archive-date= 20 February 2019 |archive-url= https://web.archive.org/web/20190220063248/http://www.51shape.com/?p=10586 |url-status= live }}</ref> By classifying each material, CIMP-3D can systematically perform 3D printing with multiple materials.<ref name="source2">{{cite conference |title=CIMP-3D |language=en |url=https://www.mri.psu.edu/mri/facilities-and-centers/cimp-3d-center-innovative-materials-processing-through-direct-digital  |access-date=18 February 2019 |archive-date=19 February 2019 |archive-url=https://web.archive.org/web/20190219130124/https://www.mri.psu.edu/mri/facilities-and-centers/cimp-3d-center-innovative-materials-processing-through-direct-digital |url-status=dead }}</ref>

=== 4D printing ===
{{main|4D printing}}
Using 3D printing&nbsp;and multi-material structures in additive manufacturing has allowed for the design and creation of what is called 4D printing. 4D printing is an additive manufacturing process in which the printed object changes shape with time, temperature, or some other type of stimulation. 4D printing allows for the creation of dynamic structures with adjustable shapes, properties or functionality. The smart/stimulus-responsive materials that are created using 4D printing can be activated to create calculated responses such as self-assembly, self-repair, multi-functionality, reconfiguration and shape-shifting. This allows for customized printing of shape-changing and shape-memory materials.<ref>Momeni, Farhang, Xun Liu, and Jun Ni. "A review of 4D printing". Materials & design 122 (2017): 42-79.</ref>

4D printing has the potential to find new applications and uses for materials (plastics, composites, metals, etc.) and has the potential to create new alloys and composites that were not viable before. The versatility of this technology and materials can lead to advances in multiple fields of industry, including space, commercial and medical fields. The repeatability, precision, and material range for 4D printing must increase to allow the process to become more practical throughout these industries.&nbsp;

To become a viable industrial production option, there are a few challenges that 4D printing must overcome. The challenges of 4D printing include the fact that the microstructures of these printed smart materials must be close to or better than the parts obtained through traditional machining processes. New and customizable materials need to be developed that have the ability to consistently respond to varying external stimuli and change to their desired shape. There is also a need to design new software for the various technique types of 4D printing. The 4D printing software will need to take into consideration the base smart material, printing technique, and structural and geometric requirements of the design.<ref>Joshi, Siddharth, et al. "4D printing of materials for the future: Opportunities and challenges." Applied Materials Today 18 (2020): 100490.</ref>

== Processes and printers ==
{{Main|3D printing processes}}
{{Summary too long|3D printing processes|date=August 2017}}

ISO/ASTM52900-15 defines seven categories of additive manufacturing (AM) processes within its meaning.<ref name=":6">{{cite journal |title=Additive manufacturing – General Principles – Overview of process categories and feedstock |journal=ISO/ASTM International Standard |date=2015 |issue=17296–2:2015(E)}}</ref><ref name=":7">{{cite web |date=1 December 2015 |title=Standard Terminology for Additive Manufacturing – General Principles – Terminology |url=http://www.astm.org/Standards/ISOASTM52900.htm |access-date=23 August 2019 |website=ASTM International – Standards Worldwide |archive-date=9 February 2019 |archive-url=https://web.archive.org/web/20190209180544/https://www.astm.org/Standards/ISOASTM52900.htm |url-status=live }}</ref> They are:
* [[3D printing processes#Stereolithography|Vat photopolymerization]]
* [[3D printing processes#Material jetting|Material jetting]]
* [[3D printing processes#Binder jetting|Binder jetting]]
* [[3D printing processes#Powder bed fusion|Powder bed fusion]]
* [[3D printing processes#Material extrusion|Material extrusion]]
* [[3D printing processes#Directed Energy Deposition (DED)|Directed energy deposition]]
* [[3D printing processes#Lamination|Sheet lamination]]

The main differences between processes are in the way layers are deposited to create parts and in the materials that are used. Each method has its own advantages and drawbacks, which is why some companies offer a choice of powder and polymer for the material used to build the object.<ref name="Auto3D-7" /> Others sometimes use standard, off-the-shelf business paper as the build material to produce a durable prototype. The main considerations in choosing a machine are generally speed, costs of the 3D printer, of the printed prototype, choice and cost of the materials, and color capabilities.<ref name="Auto3D-8" /> Printers that work directly with metals are generally expensive. However, less expensive printers can be used to make a mold, which is then used to make metal parts.<ref name="Auto3D-9" />

=== Material jetting ===
The first process where three-dimensional material is deposited to form an object was done with [[3D printing processes#Material jetting|material jetting]]<ref name=":4" /> or as it was originally called particle deposition. Particle deposition by inkjet first started with continuous inkjet technology (CIT) (1950s) and later with drop-on-demand inkjet technology (1970s) using hot-melt inks. Wax inks were the first three-dimensional materials jetted and later low-temperature alloy metal was jetted with CIT. Wax and thermoplastic hot melts were jetted next by DOD. Objects were very small and started with text characters and numerals for signage. An object must have form and can be handled. Wax characters tumbled off paper documents and inspired a liquid metal recorder patent to make metal characters for signage in 1971. Thermoplastic color inks (CMYK) were printed with layers of each color to form the first digitally formed layered objects in 1984. The idea of investment casting with Solid-Ink jetted images or patterns in 1984 led to the first patent to form articles from particle deposition in 1989, issued in 1992.

=== Material extrusion ===
[[File:Schematic representation of Fused Filament Fabrication 01.png|thumb|Schematic representation of the 3D printing technique known as fused filament fabrication; a filament "'''a)'''" of plastic material is fed through a heated moving head "'''b)'''" that melts and extrudes it depositing it, layer after layer, in the desired shape "'''c)'''. A moving platform "'''e)'''" lowers after each layer is deposited. For this kind of technology, additional vertical support structures "'''d)'''" are needed to sustain overhanging parts.]]

Some methods melt or soften the material to produce the layers. In [[fused filament fabrication]], also known as [[fused deposition modeling]] (FDM), the model or part is produced by extruding small beads or streams of material that harden immediately to form layers. A filament of [[thermoplastic]], metal wire, or other material is fed into an [[extrusion]] nozzle head ([[3D printer extruder]]), which heats the material and turns the flow on and off. FDM is somewhat restricted in the variation of shapes that may be fabricated. Another technique fuses parts of the layer and then moves upward in the working area, adding another layer of granules and repeating the process until the piece has built up. This process uses the unfused media to support overhangs and thin walls in the part being produced, which reduces the need for temporary auxiliary supports for the piece.<ref>{{cite web|title=How Selective Heat Sintering Works |url=https://thre3d.com/how-it-works/powder-bed-fusion/selective-heat-sintering-shs |publisher=THRE3D.com |access-date=3 February 2014 |archive-date=3 February 2014 |archive-url=https://web.archive.org/web/20140203071153/https://thre3d.com/how-it-works/powder-bed-fusion/selective-heat-sintering-shs}}</ref> Recently, FFF/FDM has expanded to 3-D print directly from pellets to avoid the conversion to filament. This process is called fused particle fabrication (FPF) (or fused granular fabrication (FGF) and has the potential to use more recycled materials.<ref>{{Cite journal |last1=Woern |first1=Aubrey |last2=Byard |first2=Dennis |last3=Oakley |first3=Robert |last4=Fiedler |first4=Matthew |last5=Snabes|first5=Samantha |date=12 August 2018 |title=Fused Particle Fabrication 3-D Printing: Recycled Materials' Optimization and Mechanical Properties |journal=Materials |language=en |volume=11 |issue=8 |page=1413 |doi=10.3390/ma11081413 |pmc=6120030 |pmid=30103532 |bibcode=2018Mate...11.1413W |doi-access=free}}</ref>

=== Powder bed fusion ===
Powder bed fusion techniques, or PBF, include several processes such as DMLS, [[Selective laser sintering|SLS]], [[Selective laser melting|SLM]], MJF and [[Electron-beam additive manufacturing|EBM]]. Powder bed fusion processes can be used with an array of materials and their flexibility allows for geometrically complex structures,<ref>{{Cite web |title=Powder bed fusion - DMLS, SLS, SLM, MJF, EBM |website=make.3dexperience.3ds.com |url=https://make.3dexperience.3ds.com/processes/powder-bed-fusion |access-date=10 April 2019 |archive-date=10 April 2019 |archive-url=https://web.archive.org/web/20190410104731/https://make.3dexperience.3ds.com/processes/powder-bed-fusion |url-status=live }}</ref> making it a good choice for many 3D printing projects. These techniques include [[selective laser sintering]], with both metals and polymers and [[direct metal laser sintering]].<ref name="DMLS" /> [[Selective laser melting]] does not use sintering for the fusion of powder granules but will completely melt the powder using a high-energy laser to create fully dense materials in a layer-wise method that has mechanical properties similar to those of conventional manufactured metals. [[Electron beam melting]] is a similar type of additive manufacturing technology for metal parts (e.g. [[titanium alloy]]s). EBM manufactures parts by melting metal powder layer by layer with an electron beam in a high vacuum.<ref name="Auto3D-12" /><ref name="Auto3D-13" /> Another method consists of an [[Powder bed and inkjet head 3D printing|inkjet 3D printing]] system, which creates the model one layer at a time by spreading a layer of powder ([[plaster]] or [[resin]]s) and printing a binder in the cross-section of the part using an inkjet-like process. With [[laminated object manufacturing]], thin layers are cut to shape and joined. In addition to the previously mentioned methods, [[HP Inc.|HP]] has developed the [[Multi Jet Fusion]] (MJF) which is a powder base technique, though no lasers are involved. An inkjet array applies fusing and detailing agents which are then combined by heating to create a solid layer.<ref>{{Cite web |title=Material extrusion - FDM |website=make.3dexperience.3ds.com |url=https://make.3dexperience.3ds.com/processes/material-extrusion |access-date=13 March 2019 |archive-date=9 February 2019 |archive-url=https://web.archive.org/web/20190209124107/https://make.3dexperience.3ds.com/processes/material-extrusion |url-status=live }}</ref>

=== Binder jetting ===
The binder jetting 3D printing technique involves the deposition of a binding adhesive agent onto layers of material, usually powdered, and then this "green" state part may be cured and even sintered. The materials can be ceramic-based, metal or plastic. This method is also known as [[Powder bed and inkjet head 3D printing|inkjet 3D printing]]. To produce a part, the printer builds the model using a head that moves over the platform base to spread or deposit alternating layers of powder ([[plaster]] and [[resin]]s) and binder. Most modern binder jet printers also cure each layer of binder. These steps are repeated until all layers have been printed. This green part is usually cured in an oven to off-gas most of the binder before being sintered in a kiln with a specific time-temperature curve for the given material(s).

This technology allows the printing of full-color prototypes, overhangs, and elastomer parts. The strength of bonded powder prints can be enhanced by impregnating in the spaces between the necked or sintered matrix of powder with other compatible materials depending on the powder material, like wax, [[thermoset]] polymer, or even bronze.<ref>{{Cite web|url=https://make.3dexperience.3ds.com/processes/binder-jetting|title=3DEXPERIENCE Platform|website=make.3dexperience.3ds.com|access-date=3 April 2023|archive-date=3 April 2023|archive-url=https://web.archive.org/web/20230403014128/https://make.3dexperience.3ds.com/processes/binder-jetting|url-status=live}}</ref><ref>{{cite journal |last1=Doyle |first1=Michael |last2=Agarwal |first2=Kuldeep |last3=Sealy |first3=Winston |last4=Schull |first4=Kevin |title=Effect of Layer Thickness and Orientation on Mechanical Behavior of Binder Jet Stainless Steel 420 + Bronze Parts |journal=Elsevier Procedia Manufacturing |date=2015 |volume=1 |pages=251–262 |doi=10.1016/j.promfg.2015.09.016|s2cid=138624845 |issn=2351-9789 |doi-access=free }}</ref>

[[File:Schematic representation of Stereolithography.png|thumb|upright|Schematic representation of stereolithography; a light-emitting device ''a)'' (laser or [[Digital Light Processing|DLP]]) selectively illuminate the transparent bottom ''c)'' of a tank ''b)'' filled with a liquid photo-polymerizing resin; the solidified resin ''d)'' is progressively dragged up by a lifting platform ''e)'']]

=== Stereolithography ===
Other methods cure liquid materials using different sophisticated technologies, such as [[stereolithography]]. [[Photopolymerization]] is primarily used in stereolithography to produce a solid part from a liquid. Inkjet printer systems like the ''Objet PolyJet'' system spray [[photopolymer]] materials onto a build tray in ultra-thin layers (between 16 and 30&nbsp;μm) until the part is completed.<ref name="Coward2015">{{cite book|author=Cameron Coward|title=3D Printing|url=https://books.google.com/books?id=N1cpBgAAQBAJ&pg=PT74|date=7 April 2015|publisher=DK Publishing|isbn=978-1-61564-745-3|page=74}}</ref> Each photopolymer layer is [[Curing (chemistry)|cured]] with UV light after it is jetted, producing fully cured models that can be handled and used immediately, without post-curing. Ultra-small features can be made with the 3D micro-fabrication technique used in [[two-photon absorption|multiphoton]] photopolymerisation. Due to the nonlinear nature of photo excitation, the gel is cured to a solid only in the places where the laser was focused while the remaining gel is then washed away. Feature sizes of under 100&nbsp;nm are easily produced, as well as complex structures with moving and interlocked parts.<ref name="Auto3D-15" /> Yet another approach uses a synthetic resin that is solidified using [[LED]]s.<ref name="Auto3D-16" />

In Mask-image-projection-based stereolithography, a 3D digital model is sliced by a set of horizontal planes. Each slice is converted into a two-dimensional mask image. The mask image is then projected onto a photocurable liquid resin surface and light is projected onto the resin to cure it in the shape of the layer.<ref name="k1113" /> [[Continuous liquid interface production]] begins with a pool of liquid [[photopolymer]] [[resin]]. Part of the pool bottom is transparent to [[ultraviolet light]] (the "window"), which causes the resin to solidify. The object rises slowly enough to allow the resin to flow under and maintain contact with the bottom of the object.<ref name="St. Fleur">{{cite news |url=https://www.theatlantic.com/technology/archive/2015/03/3d-printing-just-got-100-times-faster/388051/ |title=3-D Printing Just Got 100 Times Faster |last=St. Fleur |first=Nicholas |date=17 March 2015 |work=[[The Atlantic]] |access-date=19 March 2015 |archive-date=19 March 2015 |archive-url=https://web.archive.org/web/20150319200217/http://www.theatlantic.com/technology/archive/2015/03/3d-printing-just-got-100-times-faster/388051/ |url-status=live }}</ref> In powder-fed directed-energy deposition, a high-power laser is used to melt metal powder supplied to the focus of the laser beam. The powder-fed directed energy process is similar to selective laser sintering, but the metal powder is applied only where material is being added to the part at that moment.<ref>{{cite journal |doi=10.1007/s11837-015-1759-z |title=Review of Mechanical Properties of Ti-6Al-4V Made by Laser-Based Additive Manufacturing Using Powder Feedstock |journal=JOM |volume=68 |issue=3 |page=724 |year=2015 |last1=Beese |first1=Allison M. |last2=Carroll |first2=Beth E. |bibcode=2016JOM....68c.724B |s2cid=138250882 }}</ref><ref>{{cite book |doi=10.1007/978-1-4939-2113-3 |title=Additive Manufacturing Technologies |year=2015 |last1=Gibson |first1=Ian |last2=Rosen |first2=David |last3=Stucker |first3=Brent |isbn=978-1-4939-2112-6 |url=https://ris.utwente.nl/ws/files/302088833/978_3_030_56127_7.pdf }}</ref>

=== Computed axial lithography ===
[[Computed axial lithography]] is a method for 3D printing based on [[CT scan|computerised tomography scans]] to create prints in photo-curable resin. It was developed by a collaboration between the [[University of California, Berkeley]] with [[Lawrence Livermore National Laboratory]].<ref name="TomoVoluAM">{{Cite journal |last1=Kelly |first1=Brett E. |last2=Bhattacharya| first2=Indrasen |last3=Heidari |first3=Hossein |last4=Shusteff |first4=Maxim |last5=Spadaccini |first5=Christopher M. |last6=Taylor |first6=Hayden K. |date=31 January 2019 |title=Volumetric additive manufacturing via tomographic reconstruction |journal=Science |volume=363 |issue=6431 |language=en |pages=1075–1079 |doi=10.1126/science.aau7114 |issn=0036-8075 |pmid=30705152 |bibcode=2019Sci...363.1075K |s2cid=72336143 |doi-access=free}}</ref><ref name="Replicator">{{Cite web |title=Star Trek–like replicator creates entire objects in minutes |url=https://www.science.org/content/article/star-trek-replicator-creates-entire-objects-minutes |website=Science |access-date=31 January 2019 |date=31 January 2019 |archive-date=19 May 2022 |archive-url=https://web.archive.org/web/20220519203807/https://www.science.org/content/article/star-trek-replicator-creates-entire-objects-minutes |url-status=live }}</ref><ref name="Arbitrary">{{cite arXiv |last1=Kelly |first1=Brett |last2=Bhattacharya |first2=Indrasen |last3=Shusteff |first3=Maxim |last4=Panas |first4=Robert M. |last5=Taylor |first5=Hayden K. |last6=Spadaccini |first6=Christopher M. |date=16 May 2017 |title=Computed Axial Lithography (CAL): Toward Single Step 3D Printing of Arbitrary Geometries |eprint=1705.05893 |class=cs.GR}}</ref> Unlike other methods of 3D printing it does not build models through depositing layers of material like [[Fused filament fabrication|fused deposition modelling]] and [[stereolithography]], instead it creates objects using a series of 2D images projected onto a cylinder of resin.<ref name="TomoVoluAM" /><ref name="Arbitrary" /> It is notable for its ability to build an object much more quickly than other methods using resins and the ability to embed objects within the prints.<ref name="Replicator" />

=== Liquid additive manufacturing ===
[[Liquid additive manufacturing]] (LAM) is a 3D printing technique that deposits a liquid or high viscosity material (e.g. liquid silicone rubber) onto a build surface to create an object which then is [[Vulcanization|vulcanised]] using heat to harden the object.<ref name="RepRap">{{Cite web|url=https://www.3ders.org/articles/20181105-german-reprap-introduces-l280-first-liquid-additive-manufacturing-lam-production-ready-3d-printer.html|title=German RepRap introduces L280, first Liquid Additive Manufacturing (LAM) production-ready 3D printer|website=3ders.org|language=en-US|access-date=13 April 2019|archive-date=13 April 2019|archive-url=https://web.archive.org/web/20190413182253/https://www.3ders.org/articles/20181105-german-reprap-introduces-l280-first-liquid-additive-manufacturing-lam-production-ready-3d-printer.html|url-status=live}}</ref><ref>{{Cite web|url=https://www.tctmagazine.com/api/content/891e038e-dea8-11e8-a18f-120e7ad5cf50/|title=German RepRap to present series-ready Liquid Additive Manufacturing system at Formnext|last=Davies|first=Sam|date=2 November 2018|website=TCT Magazine|language=en-gb|access-date=13 April 2019}}</ref><ref>{{Cite web|url=https://www.tctmagazine.com/api/content/3a2c34f8-3571-11e7-b9f5-0aea2a882f79/|title=German RepRap presenting Liquid Additive Manufacturing technology at RAPID+TCT|date=10 May 2017|website=TCT Magazine|language=en-gb|access-date=13 April 2019}}</ref> The process was originally created by [[Adrian Bowyer]] and was then built upon by German RepRap.<ref name="RepRap" /><ref>{{Cite web|url=https://3dprint.com/229102/german-reprap-presents-liquid-additive-manufacturing-and-l280/|title=German RepRap to Present Liquid Additive Manufacturing and L280 3D Printer at Formnext|last=Scott|first=Clare|date=2 November 2018|website=3DPrint.com {{!}} The Voice of 3D Printing / Additive Manufacturing|language=en-US|access-date=13 April 2019|archive-date=13 April 2019|archive-url=https://web.archive.org/web/20190413182253/https://3dprint.com/229102/german-reprap-presents-liquid-additive-manufacturing-and-l280/|url-status=live}}</ref><ref>{{Cite web|url=https://www.tctmagazine.com/api/content/6bb17f10-7761-11e7-ba83-0a72cbefeab2/|title=German RepRap develops new polyurethane material for Liquid Additive Manufacturing|date=2 August 2017|website=TCT Magazine|language=en-gb|access-date=13 April 2019}}</ref>

A technique called ''programmable tooling'' uses 3D printing to create a temporary mold, which is then filled via a conventional [[injection molding]] process and then immediately dissolved.<ref>{{Cite web|url=https://www.makepartsfast.com/essentium-to-acquire-collider-to-advance-dlp-3d-printing-technology/|title=Essentium to acquire collider to advance DLP 3D printing technology|date=20 July 2021|website=Make Parts Fast|access-date=3 April 2023|archive-date=3 April 2023|archive-url=https://web.archive.org/web/20230403210439/https://www.makepartsfast.com/essentium-to-acquire-collider-to-advance-dlp-3d-printing-technology/|url-status=live}}</ref>

=== Lamination ===
In some printers, paper can be used as the build material, resulting in a lower cost to print. During the 1990s some companies marketed printers that cut cross-sections out of special adhesive [[coated paper]] using a carbon dioxide laser and then laminated them together.

In 2005 [[Mcor Technologies Ltd]] developed a different process using ordinary sheets of office paper, a [[tungsten carbide]] blade to cut the shape, and selective deposition of adhesive and pressure to bond the prototype.<ref name="AutoSQ-15">{{Cite web|url=http://www.rapidtoday.com/mcor.html|title=3D Printer Uses Standard Paper|website=www.rapidtoday.com|access-date=19 March 2013|archive-date=9 November 2020|archive-url=https://web.archive.org/web/20201109031803/http://www.rapidtoday.com/mcor.html|url-status=live}}</ref>

=== Directed-energy deposition (DED) ===

==== Powder-fed directed-energy deposition ====
In powder-fed directed-energy deposition (also known as [[laser metal deposition]]), a high-power laser is used to melt metal powder supplied to the focus of the laser beam. The laser beam typically travels through the center of the deposition head and is focused on a small spot by one or more lenses. The build occurs on an [[X-Y table]] which is driven by a tool path created from a digital model to fabricate an object layer by layer. The deposition head is moved up vertically as each layer is completed. Some systems even make use of 5-axis<ref>{{cite journal |last1=Yang |first1=Y. |last2=Gong |first2=Y. |last3=Qu |first3=S. |title=Additive/subtractive hybrid manufacturing of 316L stainless steel powder: Densification, microhardness and residual stress |journal=J Mech Sci Technol |date=2019 |volume=33 |issue=12 |pages=5797–5807 |doi=10.1007/s12206-019-1126-z |s2cid=214298577 |url=https://link.springer.com/article/10.1007/s12206-019-1126-z|url-access=subscription }}</ref><ref>{{cite journal |last1=Boisselier |first1=D. |last2=Sankaré |first2=S. |last3=Engel |first3=T. |title=Improvement of the Laser Direct Metal Deposition Process in 5-axis Configuration |journal=Physics Procedia |date=2014 |volume=56 |issue=8th International Conference on Laser Assisted Net Shape Engineering LANE 2014 |pages=239–249 |doi=10.1016/j.phpro.2014.08.168 |bibcode=2014PhPro..56..239B |s2cid=109491084 |doi-access=free }}</ref> or 6-axis systems<ref>{{cite journal |last1=Li |first1=L. |last2=Haghighi |first2=A. |last3=Yang |first3=Y. |title=A novel 6-axis hybrid additive-subtractive manufacturing process: Design and case studies |journal=Journal of Manufacturing Processes |date=2018 |volume=33 |pages=150–160 |doi=10.1016/j.jmapro.2018.05.008 |s2cid=139579311 |doi-access=free }}</ref> (''i.e.'' [[Articulated robot|articulated arms]]) capable of delivering material on the substrate (a printing bed, or a pre-existing part<ref>{{cite web |title=Saving with Feature Additions |url=https://www.beam-machines.com/case-studies/adding-features-isogrid |website=BeAM Machines |date=17 July 2020 |access-date=29 April 2022 |archive-date=4 July 2022 |archive-url=https://web.archive.org/web/20220704235912/https://www.beam-machines.com/case-studies/adding-features-isogrid |url-status=live }}</ref>) with few to no spatial access restrictions. Metal powder is delivered and distributed around the circumference of the head or can be split by an internal manifold and delivered through nozzles arranged in various configurations around the deposition head. A hermetically sealed chamber filled with inert gas or a local inert shroud gas (sometimes both combined) is often used to shield the melt pool from atmospheric oxygen, to limit [[Redox|oxidation]] and to better control the material properties. The powder-fed directed-energy process is similar to selective laser sintering, but the metal powder is projected only where the material is being added to the part at that moment. The laser beam is used to heat up and create a "melt pool" on the substrate, in which the new powder is injected quasi-simultaneously. The process supports a wide range of materials including titanium, stainless steel, aluminium, tungsten, and other specialty materials as well as composites and functionally graded materials. The process can not only fully build new metal parts but can also add material to existing parts for example for coatings, repair, and hybrid manufacturing applications. [[Laser engineered net shaping]] (LENS), which was developed by Sandia National Labs, is one example of the powder-fed directed-energy deposition process for 3D printing or restoring metal parts.<ref>{{Cite journal|last1=Beese|first1=Allison M.|last2=Carroll|first2=Beth E.|date=2015-12-21|title=Review of Mechanical Properties of Ti-6Al-4V Made by Laser-Based Additive Manufacturing Using Powder Feedstock|journal=JOM|volume=68|issue=3|pages=724–734|doi=10.1007/s11837-015-1759-z|issn=1047-4838|bibcode=2016JOM....68c.724B|s2cid=138250882}}</ref><ref>{{Cite book|title=Additive Manufacturing Technologies - Springer|last1=Gibson|first1=Ian|last2=Rosen|first2=David|last3=Stucker|first3=Brent|s2cid=114833020|chapter=Chapter 10|doi=10.1007/978-1-4939-2113-3|year=2015|isbn=978-1-4939-2112-6|url=https://ris.utwente.nl/ws/files/302088833/978_3_030_56127_7.pdf|access-date=14 August 2023|archive-date=29 August 2023|archive-url=https://web.archive.org/web/20230829172208/https://ris.utwente.nl/ws/files/302088833/978_3_030_56127_7.pdf|url-status=live}}</ref>

==== Metal wire processes ====
Laser-based wire-feed systems, such as laser metal deposition-wire (LMD-w), feed the wire through a nozzle that is melted by a laser using inert gas shielding in either an open environment (gas surrounding the laser) or in a sealed chamber. [[Electron beam freeform fabrication]] uses an electron beam heat source inside a vacuum chamber.

It is also possible to use conventional [[gas metal arc welding]] attached to a 3D stage to 3-D print metals such as steel, bronze and aluminium.<ref>{{cite conference|first1=Nowrin Akter|last1=Surovi|first2=Shaista|last2=Hussain|first3=Gim Song|last3=Soh|title=A Study of Machine Learning Framework for Enabling Early Defect Detection in Wire Arc Additive Manufacturing Processes|conference=International Design Engineering Technical Conferences and Computers and Information in Engineering Conference|volume=86229|number=4|pages=V03AT03A002|year=2022}}</ref><ref>{{cite journal|first1=Yuenyong|last1=Nilsiam|first2=Amberlee|last2=Haselhuhn|first3=Bas|last3=Wijnen|first4=Paul|last4=Sanders|first5=Joshua M.|last5=Pearce|title=Integrated Voltage – Current Monitoring and Control of Gas Metal Arc Weld Magnetic Ball-Jointed Open Source 3-D Printer|journal=Machines|volume=3|number=4|pages=339–51|year=2015|doi=10.3390/machines3040339|doi-access=free}}</ref> Low-cost open source [[RepRap]]-style 3-D printers have been outfitted with [[Arduino]]-based [[sensors]] and demonstrated reasonable metallurgical properties from conventional welding wire as feedstock.<ref>{{cite journal|first1=A.|last1=Pinar|first2=B. |last2=Wijnen|first3=G. C. |last3=Anzalone|first4= T. C. |last4=Havens|first5= P. G. |last5=Sanders|first6= J. M. |last6=Pearce |title=Low-cost Open-Source Voltage and Current Monitor for Gas Metal Arc Weld 3-D Printing|journal=Journal of Sensors|volume=2015|pages=1–8|year= 2015|doi=10.1155/2015/876714|doi-access=free}}<!--, Article ID 876714, 8 pages,--></ref>

=== Selective powder deposition (SPD) ===
In selective powder deposition, build and support powders are selectively deposited into a crucible, such that the build powder takes the shape of the desired object and support powder fills the rest of the volume in the crucible. Then an infill material is applied, such that it comes in contact with the build powder.  Then the crucible is fired up in a kiln at the temperature above the melting point of the infill but below the melting points of the powders. When the infill melts, it soaks the build powder. But it does not soak the support powder, because the support powder is chosen to be such that it is not wettable by the infill.  If at the firing temperature, the atoms of the infill material and the build powder are mutually defusable, such as in the case of copper powder and zinc infill, then the resulting material will be a uniform mixture of those atoms, in this case, bronze. But if the atoms are not mutually defusable, such as in the case of tungsten and copper at 1100&nbsp;°C, then the resulting material will be a composite. To prevent shape distortion, the firing temperature must be below the solidus temperature of the resulting alloy.<ref>{{cite journal |title=Validation of a low-cost selective powder deposition process through the characterization of tin bronze specimens |journal=The Journal of Materials: Design and Applications |date=2021-08-23 |doi=10.1177/14644207211031941 |last1=Magalhães |first1=Samuel |last2=Sardinha |first2=Manuel |last3=Vicente |first3=Carlos |last4=Leite |first4=Marco |last5=Ribeiro |first5=Relógio |last6=Vaz |first6=Maria |last7=Reis |first7=Luís |volume=235 |issue=12 |pages=2681–2691 |s2cid=238738655 }}</ref>

=== Cryogenic 3D printing ===
Cryogenic 3D printing is a collection of techniques that forms solid structures by freezing liquid materials while they are deposited. As each liquid layer is applied, it is cooled by the low temperature of the previous layer and printing environment which results in solidification. Unlike other 3D printing techniques, cryogenic 3D printing requires a controlled printing environment. The ambient temperature must be below the material's freezing point to ensure the structure remains solid during manufacturing and the humidity must remain low to prevent frost formation between the application of layers.<ref>{{Cite journal |last1=Li |first1=Zongan |last2=Xu |first2=Mengjia |last3=Wang |first3=Jiahang |last4=Zhang |first4=Feng |date=October 2022 |title=Recent Advances in Cryogenic 3D Printing Technologies |journal=Advanced Engineering Materials |language=en |volume=24 |issue=10 |page=2200245 |doi=10.1002/adem.202200245 |s2cid=248488161 |issn=1438-1656}}</ref> Materials typically include water and water-based solutions, such as [[brine]], [[slurry]], and [[hydrogel]]s.<ref name=":03">{{Cite journal |last1=Zhang |first1=Wei |last2=Leu |first2=Ming C |last3=Ji |first3=Zhiming |last4=Yan |first4=Yongnian |date=1999-06-01 |title=Rapid freezing prototyping with water |journal=Materials & Design |language=en |volume=20 |issue=2 |pages=139–145 |doi=10.1016/S0261-3069(99)00020-5 |issn=0261-3069}}</ref><ref>{{Cite journal |last1=Tan |first1=Zhengchu |last2=Parisi |first2=Cristian |last3=Di Silvio |first3=Lucy |last4=Dini |first4=Daniele |last5=Forte |first5=Antonio Elia |date=2017-11-24 |title=Cryogenic 3D Printing of Super Soft Hydrogels |journal=Scientific Reports |language=en |volume=7 |issue=1 |page=16293 |doi=10.1038/s41598-017-16668-9 |issn=2045-2322 |pmc=5701203 |pmid=29176756|bibcode=2017NatSR...716293T }}</ref> Cryogenic 3D printing techniques include rapid freezing prototype (RFP),<ref name=":03" /> low-temperature deposition manufacturing (LDM),<ref>{{Cite journal |last1=Xiong |first1=Zhuo |last2=Yan |first2=Yongnian |last3=Wang |first3=Shenguo |last4=Zhang |first4=Renji |last5=Zhang |first5=Chao |date=2002-06-07 |title=Fabrication of porous scaffolds for bone tissue engineering via low-temperature deposition  |journal=Scripta Materialia |language=en |volume=46 |issue=11 |pages=771–776 |doi=10.1016/S1359-6462(02)00071-4 |issn=1359-6462}}</ref> and freeze-form extrusion fabrication (FEF).<ref>{{Cite journal |last1=Huang |first1=Tieshu |last2=Mason |first2=Michael S. |last3=Hilmas |first3=Gregory E. |last4=Leu |first4=Ming C. |date=2006-06-01 |title=Freeze-form extrusion fabrication of ceramic parts |journal=Virtual and Physical Prototyping |volume=1 |issue=2 |pages=93–100 |doi=10.1080/17452750600649609 |s2cid=135763440 |issn=1745-2759}}</ref>

== Applications ==
{{Main|Applications of 3D printing}}
{{summary style section|date=December 2022}}

[[File:I robot car.jpg|thumb|The [[Audi RSQ]] was made with rapid prototyping industrial [[KUKA]] robots.]]3D printing or additive manufacturing has been used in manufacturing, medical, industry and sociocultural sectors (e.g. cultural heritage) to create successful commercial technology.<ref>{{cite journal|last1=Taufik|first1=Mohammad|last2=Jain|first2=Prashant K.|title=Additive Manufacturing: Current Scenario|url=https://www.ikbooks.com/books/book/engineering-computer-science/mechanical-production-industrial-engineering/proceedings-international-conference-on/9789385909511/|journal=Proceedings of International Conference on: Advanced Production and Industrial Engineering -ICAPIE 2016|date=10 December 2016|pages=380–386|access-date=31 May 2017|archive-date=1 October 2020|archive-url=https://web.archive.org/web/20201001182352/https://www.ikbooks.com/books/book/engineering-computer-science/mechanical-production-industrial-engineering/proceedings-international-conference-on/9789385909511/}}</ref> More recently, 3D printing has also been used in the humanitarian and development sector to produce a range of medical items, prosthetics, spares and repairs.<ref name="auto">{{Cite journal|last1=Corsini|first1=Lucia|last2=Aranda-Jan|first2=Clara B.|last3=Moultrie|first3=James|date=2019|title=Using digital fabrication tools to provide humanitarian and development aid in low-resource settings|journal=Technology in Society|language=en|volume=58|page=101117|doi=10.1016/j.techsoc.2019.02.003|url=https://www.repository.cam.ac.uk/handle/1810/290180|issn=0160-791X|doi-access=free|access-date=23 August 2019|archive-date=29 April 2023|archive-url=https://web.archive.org/web/20230429231423/https://www.repository.cam.ac.uk/handle/1810/290180|url-status=live}}</ref> The earliest application of additive manufacturing was on the [[toolroom]] end of the manufacturing spectrum. For example, [[rapid prototyping]] was one of the earliest additive variants, and its mission was to reduce the [[lead time]] and cost of developing prototypes of new parts and devices, which was earlier only done with subtractive toolroom methods such as CNC milling, turning, and precision grinding.<ref name="TMW_2011-02_Origins" /> In the 2010s, additive manufacturing entered [[production line|production]] to a much greater extent.

=== Food ===

[[3D food printing|Additive manufacturing of food]] is being developed by squeezing out food, layer by layer, into three-dimensional objects. A large variety of foods are appropriate candidates, such as chocolate and candy, and flat foods such as crackers, pasta,<ref name="AutoSQ-72" /> and pizza.<ref>{{cite web| title = Did BeeHex Just Hit "Print" to Make Pizza at Home?| url = http://www.huffingtonpost.co.uk/cohan-chew/did-beehex-just-hit-print_b_10108424.html| access-date = 28 May 2016| date = 27 May 2016| archive-date = 21 February 2023| archive-url = https://web.archive.org/web/20230221012417/https://www.huffingtonpost.co.uk/cohan-chew/did-beehex-just-hit-print_b_10108424.html| url-status = live}}</ref><ref>{{cite web|title=Foodini 3D Printer Cooks Up Meals Like the Star Trek Food Replicator|url=http://inhabitat.com/foodini-3d-printer-will-make-all-your-meals-for-you-like-the-star-trek-food-replicator|access-date=27 January 2015|archive-date=2 May 2020|archive-url=https://web.archive.org/web/20200502163656/https://inhabitat.com/foodini-3d-printer-will-make-all-your-meals-for-you-like-the-star-trek-food-replicator/}}</ref> [[NASA]] is looking into the technology in order to create 3D-printed food to limit [[food waste]] and to make food that is designed to fit an astronaut's dietary needs.<ref>{{Cite web|url=https://sbir.gsfc.nasa.gov/SBIR/abstracts/12/sbir/phase1/SBIR-12-1-H12.04-9357.html?solicitationId=SBIR_12_P1.|title=3D Printed Food System for Long Duration Space Missions|website=sbir.gsfc.nasa.gov|access-date=24 April 2019|archive-date=24 July 2020|archive-url=https://web.archive.org/web/20200724193456/https://sbir.gsfc.nasa.gov/SBIR/abstracts/12/sbir/phase1/SBIR-12-1-H12.04-9357.html?solicitationId=SBIR_12_P1.|url-status=live}}</ref> In 2018, Italian bioengineer [[Giuseppe Scionti]] developed a technology allowing the production of fibrous plant-based meat analogues using a custom [[3D bioprinting|3D bioprinter]], mimicking meat texture and nutritional values.<ref>{{Cite news|url=https://elpais.com/elpais/2018/09/27/inenglish/1538061240_449222.html|title=Barcelona researcher develops 3D printer that makes 'steaks'|last=Bejerano|first=Pablo G.|date=28 September 2018|work=El País|access-date=21 June 2019|language=en|issn=1134-6582|archive-date=25 December 2019|archive-url=https://web.archive.org/web/20191225005146/https://elpais.com/elpais/2018/09/27/inenglish/1538061240_449222.html|url-status=live}}</ref><ref>{{Cite news|url=https://www.businessinsider.com/this-fake-meat-is-printed-in-a-lab-using-vegetables-and-a-3d-printer-2018-11|title=A researcher has developed a plant-based meat substitute that's made with a 3D printer|author1=Lidia Montes|author2=Ruqayyah Moynihan|website=[[Business Insider]]|access-date=21 June 2019|archive-date=15 November 2023|archive-url=https://web.archive.org/web/20231115145309/https://www.businessinsider.com/this-fake-meat-is-printed-in-a-lab-using-vegetables-and-a-3d-printer-2018-11|url-status=live}}</ref>

=== Fashion ===
[[File:Ted Noten Fashionista in green 2009.jpg|thumb|3D-printed necklace]]3D printing has entered the world of clothing, with fashion designers experimenting with 3D-printed bikinis, shoes, and dresses.<ref name="resins-online.com" /> In commercial production, [[Nike (company)|Nike]] used 3D printing to prototype and manufacture the 2012 Vapor Laser Talon football shoe for players of American football, and [[New Balance]] has 3D manufactured custom-fit shoes for athletes.<ref name="resins-online.com" /><ref name="AutoSQ-45" /> 3D printing has come to the point where companies are printing consumer-grade eyewear with on-demand custom fit and styling (although they cannot print the lenses). On-demand customization of glasses is possible with rapid prototyping.<ref name="Forbes.com" />

=== Transportation ===
[[File:HCC 3D printed turbine view 1.jpg|thumb|A 3D-printed jet engine model]]
In cars, trucks, and aircraft, additive manufacturing is beginning to transform both [[unibody]] and [[fuselage]] design and production, and [[powertrain]] design and production. For example, [[General Electric]] uses high-end 3D printers to build parts for [[turbine]]s.<ref name="cfr2013" /> Many of these systems are used for rapid prototyping before mass production methods are employed. Other prominent examples include:
* In early 2014, Swedish [[supercar]] manufacturer [[Koenigsegg]] announced the One:1, a supercar that utilizes many components that were 3D printed.<ref name="AutoSQ-36" /> [[Urbee]] is the first car produced using 3D printing (the bodywork and car windows were "printed").<ref>{{Cite web|url=https://www.tecmundo.com.br/impressora/6260-conheca-o-urbee-primeiro-carro-a-ser-fabricado-com-uma-impressora-3d.htm|title=Conheça o Urbee, primeiro carro a ser fabricado com uma impressora 3D|website=tecmundo.com.br|date=3 November 2010 }}</ref><ref>{{cite web|url=http://truth-out.org/news/item/27430-the-urbee-3d-printed-car-coast-to-coast-on-10-gallons|title=The ''Urbee'' 3D-Printed Car: Coast to Coast on 10 Gallons?|first=Max|last=Eternity|date=23 November 2014 }}</ref><ref>{{youTube|id=vI12MqoYQto|title= 3D Printed Car Creator Discusses Future of the Urbee}}</ref>
* In 2014, [[Local Motors]] debuted Strati, a functioning vehicle that was entirely 3D printed using ABS plastic and carbon fiber, except the powertrain.<ref>{{cite web|url=http://fortune.com/2015/01/13/local-motors-shows-strati-the-worlds-first-3d-printed-car/|title=Local Motors shows Strati, the world's first 3D-printed car|date=13 January 2015|access-date=21 July 2016|archive-date=29 June 2016|archive-url=https://web.archive.org/web/20160629111808/http://fortune.com/2015/01/13/local-motors-shows-strati-the-worlds-first-3d-printed-car/|url-status=live}}</ref>
* In May 2015 Airbus announced that its new [[Airbus A350 XWB]] included over 1000 components manufactured by 3D printing.<ref>{{cite web|title=Airbus had 1,000 parts 3D printed to meet deadline|url=https://www.bbc.com/news/technology-32597809|access-date=27 November 2015|date=6 May 2015|first=Dan|last=Simmons|publisher=BBC|archive-date=4 November 2020|archive-url=https://web.archive.org/web/20201104031334/https://www.bbc.com/news/technology-32597809|url-status=live}}</ref>
* In 2015, a [[Royal Air Force]] [[Eurofighter Typhoon]] fighter jet flew with printed parts. The [[United States Air Force]] has begun to work with 3D printers, and the [[Israeli Air Force]] has also purchased a 3D printer to print spare parts.<ref>{{cite news|title=The 3D printer revolution comes to the IAF|url=http://www.ynetnews.com/articles/0,7340,L-4684682,00.html|access-date=29 September 2015|date=27 July 2015|first=Yoav|last=Zitun|newspaper=Ynetnews|publisher=Ynet News|archive-date=29 September 2015|archive-url=https://web.archive.org/web/20150929054414/http://www.ynetnews.com/articles/0,7340,L-4684682,00.html|url-status=live}}</ref>
* In 2017, [[GE Aviation]] revealed that it had used [[design for additive manufacturing]] to create a helicopter engine with 16 parts instead of 900, with great potential impact on reducing the complexity of [[supply chain]]s.<ref name="Zelinski_2017-03-31">{{Citation |last=Zelinski |first=Peter |date=31 March 2017 |title=GE team secretly printed a helicopter engine, replacing 900 parts with 16 |journal=Modern Machine Shop |url=http://www.additivemanufacturing.media/blog/post/ge-team-secretly-printed-a-helicopter-engine-replacing-900-parts-with-16 |access-date=9 April 2017 |postscript=.}}</ref>

=== Firearms ===

AM's impact on firearms involves two dimensions: new manufacturing methods for established companies, and new possibilities for the making of [[do-it-yourself]] firearms. In 2012, the US-based group [[Defense Distributed]] disclosed plans to design a working plastic [[3D printed firearms|3D-printed firearm]] "that could be downloaded and reproduced by anybody with a 3D printer".<ref name="f20120823" /><ref name="pcm20120824" /> After Defense Distributed released their plans, questions were raised regarding the effects that 3D printing and widespread consumer-level [[CNC]] machining<ref name="AutoSQ-54" /><ref name="AutoSQ-55" /> may have on [[gun control]] effectiveness.<ref name="AutoSQ-56" /><ref name="AutoSQ-57" /><ref name="AutoSQ-58" /><ref name="AutoSQ-59" /> Moreover, armor-design strategies can be enhanced by taking inspiration from nature and prototyping those designs easily, using AM.<ref>{{cite journal |last1=Islam |first1=Muhammed Kamrul |last2=Hazell |first2=Paul J. |last3=Escobedo |first3=Juan P. |last4=Wang |first4=Hongxu |title=Biomimetic armour design strategies for additive manufacturing: A review |journal=Materials & Design |date=July 2021 |volume=205 |page=109730 |doi=10.1016/j.matdes.2021.109730|doi-access=free }}</ref>

=== Health ===

Surgical uses of 3D printing-centric therapies began in the mid-1990s with anatomical modeling for bony reconstructive surgery planning. Patient-matched implants were a natural extension of this work, leading to truly personalized implants that fit one unique individual.<ref>{{cite journal|last2=Sadove|first2=A. M.|date=1 November 1998|title=Computer-generated patient models for reconstruction of cranial and facial deformities|journal=J Craniofac Surg|volume=9|issue=6|pages=548–556 |doi=10.1097/00001665-199811000-00011|pmid=10029769 |first1=B. L.|last1=Eppley}}</ref> Virtual planning of surgery and guidance using 3D printed, personalized instruments have been applied to many areas of surgery including total joint replacement and craniomaxillofacial reconstruction with great success.<ref>{{cite journal |last=Poukens|first=Jules|date=1 February 2008|title=A classification of cranial implants based on the degree of difficulty in computer design and manufacture|journal=The International Journal of Medical Robotics and Computer Assisted Surgery|volume=4|issue=1|pages=46–50 |doi=10.1002/rcs.171 |pmid=18240335 |s2cid=26121479}}</ref><ref name="AutoSQ-50" /> One example of this is the bioresorbable trachial splint to treat newborns with tracheobronchomalacia<ref>{{cite journal |doi=10.1056/NEJMc1206319 |pmid=23697530 |title=Bioresorbable Airway Splint Created with a Three-Dimensional Printer |journal=New England Journal of Medicine |volume=368 |issue=21 |pages=2043–5 |year=2013 |last1=Zopf |first1=David A. |last2=Hollister |first2=Scott J. |last3=Nelson |first3=Marc E. |last4=Ohye |first4=Richard G. |last5=Green |first5=Glenn E. |doi-access=free }}</ref> developed at the University of Michigan. The use of additive manufacturing for serialized production of orthopedic implants (metals) is also increasing due to the ability to efficiently create porous surface structures that facilitate [[osseointegration]]. The hearing aid and dental industries are expected to be the biggest areas of future development using custom 3D printing technology.<ref name="AutoSQ-49" />

3D printing is not just limited to inorganic materials; there have been a number of biomedical advancements made possible by 3D printing. {{As of|2012}}, 3D [[bio-printing]] technology has been studied by [[biotechnology]] firms and academia for possible use in tissue engineering applications in which organs and body parts are built using [[inkjet printing]] techniques. In this process, layers of living cells are deposited onto a gel medium or sugar matrix and slowly built up to form three-dimensional structures including vascular systems.<ref name="Auto3D-38" /> 3D printing has been considered as a method of implanting [[Gene therapy|stem cells]] capable of generating new tissues and organs in living humans.<ref>{{cite web |title=RFA-HD-15-023: Use of 3-D Printers for the Production of Medical Devices (R43/R44) |url=http://grants.nih.gov/grants/guide/rfa-files/RFA-HD-15-023.html |access-date=2015-09-30 |publisher=NIH grants |archive-date=31 March 2023 |archive-url=https://web.archive.org/web/20230331010308/http://grants.nih.gov/grants/guide/rfa-files/RFA-HD-15-023.html |url-status=live }}</ref> In 2018, 3D printing technology was used for the first time to create a matrix for cell immobilization in fermentation. Propionic acid production by ''Propionibacterium acidipropionici'' immobilized on 3D-printed nylon beads was chosen as a model study. It was shown that those 3D-printed beads were capable of promoting high-density cell attachment and propionic acid production, which could be adapted to other fermentation bioprocesses.<ref>{{Cite journal |last1=Belgrano |first1=Fabricio dos Santos |last2=Diegel |first2=Olaf |last3=Pereira |first3=Nei |last4=Hatti-Kaul |first4=Rajni |year=2018 |title=Cell immobilization on 3D-printed matrices: A model study on propionic acid fermentation |journal=Bioresource Technology |volume=249 |pages=777–782 |doi=10.1016/j.biortech.2017.10.087 |pmid=29136932|bibcode=2018BiTec.249..777B }}</ref>

3D printing has also been employed by researchers in the pharmaceutical field. During the last few years, there has been a surge in academic interest regarding drug delivery with the aid of AM techniques. This technology offers a unique way for materials to be utilized in novel formulations.<ref>{{Cite journal |last1=Melocchi |first1=Alice |last2=Uboldi |first2=Marco |last3=Cerea |first3=Matteo |last4=Foppoli |first4=Anastasia |last5=Maroni |first5=Alessandra |last6=Moutaharrik |first6=Saliha |last7=Palugan |first7=Luca |last8=Zema |first8=Lucia |last9=Gazzaniga |first9=Andrea |date=2020-10-01 |title=A Graphical Review on the Escalation of Fused Deposition Modeling (FDM) 3D Printing in the Pharmaceutical Field |journal=Journal of Pharmaceutical Sciences |language=en |volume=109 |issue=10 |pages=2943–2957 |doi=10.1016/j.xphs.2020.07.011 |pmid=32679215 |hdl=2434/828138 |s2cid=220630295 |issn=0022-3549|doi-access=free |hdl-access=free }}</ref> AM manufacturing allows for the usage of materials and compounds in the development of formulations, in ways that are not possible with conventional/traditional techniques in the pharmaceutical field, e.g. tableting, cast-molding, etc. Moreover, one of the major advantages of 3D printing, especially in the case of fused deposition modelling (FDM), is the personalization of the dosage form that can be achieved, thus, targeting the patient's specific needs.<ref>{{Cite journal |last1=Afsana |last2=Jain |first2=Vineet |last3=Haider |first3=Nafis |last4=Jain |first4=Keerti |date=2019-03-20 |title=3D Printing in Personalized Drug Delivery |url=http://www.eurekaselect.com/170028/article |journal=Current Pharmaceutical Design |language=en |volume=24 |issue=42 |pages=5062–5071 |doi=10.2174/1381612825666190215122208 |pmid=30767736 |s2cid=73421860|url-access=subscription }}</ref> In the not-so-distant future, 3D printers are expected to reach hospitals and pharmacies in order to provide on-demand production of personalized formulations according to the patients' needs.<ref>{{Cite journal |last1=Trenfield |first1=Sarah J |last2=Awad |first2=Atheer |last3=Madla |first3=Christine M |last4=Hatton |first4=Grace B |last5=Firth |first5=Jack |last6=Goyanes |first6=Alvaro |last7=Gaisford |first7=Simon |last8=Basit |first8=Abdul W |date=2019-10-03 |title=Shaping the future: recent advances of 3D printing in drug delivery and healthcare |journal=Expert Opinion on Drug Delivery |language=en |volume=16 |issue=10 |pages=1081–1094 |doi=10.1080/17425247.2019.1660318 |pmid=31478752 |s2cid=201805196 |issn=1742-5247 |url=https://discovery.ucl.ac.uk/id/eprint/10082473/1/Gaisford_AAM_Shaping%20the%20future-%20Recent%20advances%20of%203D%20printing%20in%20drug%20delivery%20and%20healthcare%20R1.pdf |access-date=5 October 2020 |archive-date=7 November 2020 |archive-url=https://web.archive.org/web/20201107110244/https://discovery.ucl.ac.uk/id/eprint/10082473/1/Gaisford_AAM_Shaping%20the%20future-%20Recent%20advances%20of%203D%20printing%20in%20drug%20delivery%20and%20healthcare%20R1.pdf |url-status=live }}</ref>

3D printing has also been used for medical equipment. During the [[COVID-19 pandemic]] 3D printers were used to supplement the strained supply of [[Personal protective equipment|PPE]] through volunteers using their personally owned printers to produce various pieces of personal protective equipment (i.e. frames for face shields).

=== Education ===

3D printing, and open source 3D printers, in particular, are the latest technologies making inroads into the classroom.<ref>Schelly, C., Anzalone, G., Wijnen, B., & Pearce, J. M. (2015). "Open-source 3-D printing Technologies for education: Bringing Additive Manufacturing to the Classroom". ''Journal of Visual Languages & Computing''.</ref><ref>Grujović, N., Radović, M., Kanjevac, V., Borota, J., Grujović, G., & Divac, D. (September 2011). "3D printing technology in education environment." In ''34th International Conference on Production Engineering'' (pp. 29–30).</ref><ref>{{cite book |doi=10.1109/ISECon.2014.6891037 |chapter=An educational venture into 3D Printing |title=2014 IEEE Integrated STEM Education Conference |pages=1–6 |year=2014 |last1=Mercuri |first1=Rebecca |last2=Meredith |first2=Kevin |isbn=978-1-4799-3229-0 |s2cid=16555348 }}</ref>  Higher education has proven to be a major buyer of desktop and professional 3D printers which industry experts generally view as a positive indicator.<ref>{{cite web |date=2 December 2015 |title=Despite Market Woes, 3D Printing Has a Future Thanks to Higher Education – Bold |url=http://bold.global/jordan-brehove/2015/12/02/despite-market-woes-3d-printing-has-a-future-thanks-to-higher-education/ |access-date=1 April 2016 |archive-date=30 March 2016 |archive-url=https://web.archive.org/web/20160330222234/http://bold.global/jordan-brehove/2015/12/02/despite-market-woes-3d-printing-has-a-future-thanks-to-higher-education/ |url-status=live }}</ref> Some authors have claimed that 3D printers offer an unprecedented "revolution" in [[Science, Technology, Engineering, and Math|STEM]] education.<ref>{{Cite journal |last1=Oppliger |first1=Douglas E. |last2=Anzalone |first2=Gerald |last3=Pearce |first3=Joshua M. |last4=Irwin |first4=John L. |date=15 June 2014 |title=The RepRap 3-D Printer Revolution in STEM Education |url=https://peer.asee.org/the-reprap-3-d-printer-revolution-in-stem-education |journal=2014 ASEE Annual Conference & Exposition |pages=24.1242.1–24.1242.13 |issn=2153-5868 |access-date=23 August 2019 |archive-date=7 July 2023 |archive-url=https://web.archive.org/web/20230707112920/https://peer.asee.org/the-reprap-3-d-printer-revolution-in-stem-education |url-status=live }}</ref><ref>{{Cite journal |last=Gillen |first=Andrew |date=2016 |title=Teacher's Toolkit: The New Standard in Technology Education: 3-D Design Class |journal=Science Scope |volume=039 |issue=9 |pages=8–15 |doi=10.2505/4/ss16_039_09_8 |issn=0887-2376}}</ref> The evidence for such claims comes from both the low-cost ability for [[rapid prototyping]] in the classroom by students, but also the fabrication of low-cost high-quality scientific equipment from [[open hardware]] designs forming [[open-source labs]].<ref name="AutoSQ-68" /> Additionally, Libraries around the world have also become locations to house smaller 3D printers for educational and community access.<ref>{{cite web |date=2 April 2015 |title=UMass Amherst Library Opens 3-D Printing Innovation Center |url=http://lj.libraryjournal.com/2015/03/technology/umass-amherst-library-opens-3d-printing-innovation-center/ |archive-url=https://web.archive.org/web/20150402221847/http://lj.libraryjournal.com/2015/03/technology/umass-amherst-library-opens-3d-printing-innovation-center/ |archive-date=2 April 2015 |access-date=23 August 2019 |website=Library Journal}}</ref> Future applications for 3D printing might include creating open-source scientific equipment.<ref name="AutoSQ-68" /><ref name="AutoQK-4" />[[File:3D Printed Ancient Egyptian Figurine.png|thumb|upright|3D-printed sculpture of an Egyptian pharaoh shown at [[Threeding]]]]

=== Replicating archeological artifacts ===

In the 2010s, 3D printing became intensively used in the [[cultural heritage]] field for preservation, restoration and dissemination purposes.<ref>{{cite journal |doi=10.1111/cgf.12781 |title=Digital Fabrication Techniques for Cultural Heritage: A Survey] |journal=Computer Graphics Forum |volume=36 |issue=1 |pages=6–21 |year=2017 |url=http://vcg.isti.cnr.it/Publications/2017/SCPCD17/DigitalFabricationForCH.pdf |last1=Scopigno |first1=R. |last2=Cignoni |first2=P. |last3=Pietroni |first3=N. |last4=Callieri |first4=M. |last5=Dellepiane |first5=M. |s2cid=26690232 |access-date=12 April 2017 |archive-date=12 April 2017 |archive-url=https://web.archive.org/web/20170412224522/http://vcg.isti.cnr.it/Publications/2017/SCPCD17/DigitalFabricationForCH.pdf |url-status=live }}</ref> Many Europeans and North American Museums have purchased 3D printers and actively recreate missing pieces of their relics<ref>{{cite web|url=http://www.3ders.org/articles/20150714-museum-uses-3d-printing-to-take-fragile-maquette-by-thomas-hart-benton-on-tour.html |title=Museum uses 3D printing to take fragile maquette by Thomas Hart Benton on tour through the States |archive-url=https://web.archive.org/web/20151117014241/http://www.3ders.org/articles/20150714-museum-uses-3d-printing-to-take-fragile-maquette-by-thomas-hart-benton-on-tour.html |archive-date=17 November 2015 }}</ref> and archaeological monuments such as [[Tiwanaku]] in [[Bolivia]].<ref>{{cite journal |last1=Vranich |first1=Alexei |title=Reconstructing ancient architecture at Tiwanaku, Bolivia: the potential and promise of 3D printing |journal=Heritage Science |date=December 2018 |volume=6 |issue=1 |page=65 |doi=10.1186/s40494-018-0231-0|s2cid=139309556 |doi-access=free }}</ref> The [[Metropolitan Museum of Art]] and the [[British Museum]] have started using their 3D printers to create museum souvenirs that are available in the museum shops.<ref>{{cite web|url=https://www.independent.co.uk/life-style/gadgets-and-tech/british-museum-releases-scans-of-artefacts-to-let-you-3d-print-your-own-museum-at-home-9837654.html |archive-url=https://web.archive.org/web/20141107012216/http://www.independent.co.uk/life-style/gadgets-and-tech/british-museum-releases-scans-of-artefacts-to-let-you-3d-print-your-own-museum-at-home-9837654.html |archive-date=2014-11-07 |url-access=limited |url-status=live|title=British Museum releases 3D printer scans of artefacts|website=[[Independent.co.uk]]|date=4 November 2014 }}</ref> Other museums, like the National Museum of Military History and Varna Historical Museum, have gone further and sell through the online platform [[Threeding]] digital models of their artifacts, created using [[Artec 3D]] scanners, in 3D printing friendly file format, which everyone can 3D print at home.<ref>{{cite web|url=http://3dprint.com/45699/threeding-artec-museum/|title=Threeding Uses Artec 3D Scanning Technology to Catalog 3D Models for Bulgaria's National Museum of Military History|date=20 February 2015|publisher=3dprint.com|access-date=13 November 2015|archive-date=17 November 2015|archive-url=https://web.archive.org/web/20151117030659/http://3dprint.com/45699/threeding-artec-museum/|url-status=live}}</ref> [[Morehshin Allahyari]], an Iranian-born U.S. artist, considers her use of 3D sculpting processes of re-constructing Iranian cultural treasures as feminist activism. Allahyari uses a 3D modeling software to reconstruct a series of cultural artifacts that were demolished by ISIS militants in 2014.<ref>Soulellis, P. (2017). Material Speculation: ISIS. In M. Allahyari & D. Rourke (Eds.), The 3D Additivist Cookbook (pp. 129–131). Institute of Network Cultures.</ref>

===Replicating historic buildings and architectural structures===
[[Image:Stoofbrug-JUL2021-3Dbridge.jpg|thumb|The {{Ill|Stoofbrug|nl}} in Amsterdam, the world's first 3D-printed metal bridge<ref name="euronews.com" />]]
The application of 3D printing for the representation of architectural assets has many challenges. In 2018, the structure of [[Bank Melli Iran#Bank Melli Iran Museum|Iran National Bank]] was traditionally surveyed and modeled in computer graphics software (specifically, [[Cinema4D]]) and was optimized for 3D printing. The team tested the technique for the construction of the part and it was successful. After testing the procedure, the modellers reconstructed the structure in Cinema4D and exported the front part of the model to [[Netfabb]]. The entrance of the building was chosen due to the 3D printing limitations and the budget of the project for producing the maquette. 3D printing was only one of the capabilities enabled by the produced 3D model of the bank, but due to the project's limited scope, the team did not continue modelling for the virtual representation or other applications.<ref name="BST">{{cite journal |doi=10.16995/bst.364 |title=Production of Iranian Architectural Assets for Representation in Museums: Theme of Museum-Based Digital Twin |journal=Body, Space and Technology |volume=20 |issue=1 |pages=61–74 |year=2021 |last1=Parsinejad |first1=H. |last2=Choi |first2=I. |last3=Yari |first3=M.|doi-access=free }}</ref> In 2021, Parsinejad et al. comprehensively compared the hand surveying method for 3D reconstruction ready for 3D printing with digital recording (adoption of photogrammetry method).<ref name="BST" />

The world's first 3D-printed steel bridge was unveiled in [[Amsterdam]] in July 2021. Spanning 12 meters over the [[Oudezijds Achterburgwal]] canal, the bridge was created using robotic arms that printed over 4,500 kilograms of stainless steel. It took six months to complete.<ref>{{Cite web |title= First 3D Printed Footbridge In Amsterdam Revealed To The Public - NPR |url= https://www.npr.org/2021/08/27/1031253065/first-3d-printed-steel-bridge-in-europe |access-date=2024-09-09 |website= npr.org |date= 27 August 2021 |last1= Franklin |first1= Jonathan }}</ref>

===Soft actuators ===

3D printed soft [[actuators]] is a growing application of 3D printing technology that has found its place in the 3D printing applications. These soft actuators are being developed to deal with soft structures and organs, especially in biomedical sectors and where the interaction between humans and robots is inevitable. The majority of the existing soft actuators are fabricated by conventional methods that require manual fabrication of devices, post-processing/assembly, and lengthy iterations until the maturity of the fabrication is achieved. Instead of the tedious and time-consuming aspects of the current fabrication processes, researchers are exploring an appropriate manufacturing approach for the effective fabrication of soft actuators. Thus, 3D-printed soft actuators are introduced to revolutionize the design and fabrication of soft actuators with custom geometrical, functional, and control properties in a faster and inexpensive approach. They also enable incorporation of all actuator components into a single structure eliminating the need to use external [[joint]]s, [[adhesive]]s, and [[fastener]]s.

===Circuit boards===
Circuit board manufacturing involves multiple steps which include imaging, drilling, plating, solder mask coating, nomenclature printing and surface finishes. These steps include many chemicals such as harsh solvents and acids. 3D printing circuit boards remove the need for many of these steps while still producing complex designs.<ref>{{Cite web|url=http://shortsleeveandtieclub.com/3d-printed-circuit-boards-are-the-next-big-thing-in-additive-manufacturing/|title=3D Printed Circuit Boards are the Next Big Thing in Additive Manufacturing|date=20 June 2018|access-date=24 April 2019|archive-date=24 April 2019|archive-url=https://web.archive.org/web/20190424233926/http://shortsleeveandtieclub.com/3d-printed-circuit-boards-are-the-next-big-thing-in-additive-manufacturing/}}</ref> Polymer ink is used to create the layers of the build while silver polymer is used for creating the traces and holes used to allow electricity to flow.<ref>{{Cite web|url=https://www.nano-di.com/materials|title=Additive Manufacturing Inks & Materials for Custom 3D Printing Solutions|website=nano-di.com}}</ref> Current circuit board manufacturing can be a tedious process depending on the design. Specified materials are gathered and sent into inner layer processing where images are printed, developed and etched. The etch cores are typically punched to add lamination tooling. The cores are then prepared for lamination. The stack-up, the buildup of a circuit board, is built and sent into lamination where the layers are bonded. The boards are then measured and drilled. Many steps may differ from this stage however for simple designs, the material goes through a plating process to plate the holes and surface. The outer image is then printed, developed and etched. After the image is defined, the material must get coated with a solder mask for later soldering. Nomenclature is then added so components can be identified later. Then the surface finish is added. The boards are routed out of panel form into their singular or array form and then electrically tested. Aside from the paperwork that must be completed which proves the boards meet specifications, the boards are then packed and shipped. The benefits of 3D printing would be that the final outline is defined from the beginning, no imaging, punching or lamination is required and electrical connections are made with the silver polymer which eliminates drilling and plating. The final paperwork would also be greatly reduced due to the lack of materials required to build the circuit board. Complex designs which may take weeks to complete through normal processing can be 3D printed, greatly reducing manufacturing time.[[File:3D selfie in 1 20 scale in my palm after one spray of clear satin acrylic varnish IMG 4751 FRD.jpg|thumb|upright|A [[3D selfie]] in 1:20 scale printed using gypsum-based printing]]

===Hobbyists===
In 2005, academic journals began to report on the possible artistic applications of 3D printing technology.<ref name="Auto3D-34" /> Off-the-shelf machines were increasingly capable of producing practical household applications, for example, ornamental objects. Some practical examples include a working clock<ref name="Auto3D-21" /> and [[gear]]s printed for home woodworking machines among other purposes.<ref name="Auto3D-23" /> Websites associated with home 3D printing tended to include backscratchers, coat hooks, door knobs, etc.<ref>{{Cite web |title="backscratcher" 3D Models to Print – yeggi |url=https://www.yeggi.com/q/backscratcher/?s=tt |website=yeggi.com |access-date=23 August 2019 |archive-date=28 November 2020 |archive-url=https://web.archive.org/web/20201128102045/https://www.yeggi.com/q/backscratcher/?s=tt |url-status=live }}</ref> As of 2017, domestic 3D printing was reaching a consumer audience beyond hobbyists and enthusiasts. Several projects and companies are making efforts to develop affordable 3D printers for home desktop use. Much of this work has been driven by and targeted at [[Do it yourself|DIY]]/[[Maker culture|maker]]/enthusiast/[[early adopter]] communities, with additional ties to the academic and [[Hacker (hobbyist)|hacker]] communities.

Sped on by decreases in price and increases in quality, {{as of|2019}} an estimated 2 million people worldwide have purchased a 3D printer for hobby use.<ref>Congressional Research Service. "3D Printing: Overview, Impacts, and the Federal Role" (August 2, 2019) Fas.org</ref>

== Legal aspects ==

=== Intellectual property ===
{{See also|Open-source hardware}}
3D printing has existed for decades within certain manufacturing industries where many legal regimes, including [[patent]]s, [[industrial design right]]s, [[copyright]]s, and [[trademark]]s may apply. However, there is not much [[jurisprudence]] to say how these laws will apply if 3D printers become mainstream and individuals or hobbyist communities begin manufacturing items for personal use, for non-profit distribution, or for sale.

Any of the mentioned legal regimes may prohibit the distribution of the designs used in 3D printing or the distribution or sale of the printed item. To be allowed to do these things, where active intellectual property was involved, a person would have to contact the owner and ask for a licence, which may come with conditions and a price. However, many patent, design and copyright laws contain a standard limitation or exception for "private" or "non-commercial" use of inventions, designs or works of art protected under intellectual property (IP). That standard limitation or exception may leave such private, non-commercial uses outside the scope of IP rights.

Patents cover inventions including processes, machines, manufacturing, and compositions of matter and have a finite duration which varies between countries, but generally 20 years from the date of application. Therefore, if a type of wheel is patented, printing, using, or selling such a wheel could be an infringement of the patent.<ref name="AutoSQ-82" />

Copyright covers an expression<ref name="wired" /> in a tangible, fixed medium and often lasts for the life of the author plus 70&nbsp;years thereafter.<ref name="deal" /> For example, a sculptor retains copyright over a statue, such that other people cannot then legally distribute designs to print an identical or similar statue without paying royalties, waiting for the copyright to expire, or working within a [[fair use]] exception.

When a feature has both artistic (copyrightable) and functional (patentable) merits when the question has appeared in US court, the courts have often held the feature is not copyrightable unless it can be separated from the functional aspects of the item.<ref name="deal" /> In other countries the law and the courts may apply a different approach allowing, for example, the design of a useful device to be registered (as a whole) as an industrial design on the understanding that, in case of unauthorized copying, only the non-functional features may be claimed under design law whereas any technical features could only be claimed if covered by a valid patent.

=== Gun legislation and administration ===
{{Main|3D printed firearms}}
The US [[United States Department of Homeland Security|Department of Homeland Security]] and the [[Joint Regional Intelligence Center]] released a memo stating that "significant advances in three-dimensional (3D) printing capabilities, availability of free digital 3D printable files for firearms components, and difficulty regulating file sharing may present public safety risks from unqualified gun seekers who obtain or manufacture 3D printed guns" and that "proposed legislation to ban 3D printing of weapons may deter, but cannot completely prevent their production. Even if the practice is prohibited by new legislation, online distribution of these 3D printable files will be as difficult to control as any other illegally traded music, movie or software files."<ref name="AutoSQ-83" />

Attempting to restrict the distribution of gun plans via the Internet has been likened to the futility of preventing the widespread distribution of [[DeCSS]], which enabled DVD [[ripping]].<ref name="AutoSQ-90" /><ref name="AutoSQ-91" /><ref name="AutoSQ-92" /><ref name="AutoSQ-93" /> After the US government had Defense Distributed take down the plans, they were still widely available via the [[The Pirate Bay|Pirate Bay]] and other file sharing sites.<ref name="AutoSQ-94" /> Downloads of the plans from the UK, Germany, Spain, and Brazil were heavy.<ref name="AutoSQ-88" /><ref name="AutoSQ-89" /> Some US legislators have proposed regulations on 3D printers to prevent them from being used for printing guns.<ref name="AutoSQ-95" /><ref name="AutoSQ-96" /> 3D printing advocates have suggested that such regulations would be futile, could cripple the 3D printing industry and could infringe on free speech rights, with early pioneers of 3D printing professor [[Hod Lipson]] suggesting that gunpowder could be controlled instead.<ref name="AutoSQ-97" /><ref name="AutoSQ-98" /><ref name="AutoSQ-99" /><ref name="AutoSQ-101" /><ref name="AutoSQ-102" /><ref name="AutoSQ-103" />

Internationally, where gun controls are generally stricter than in the United States, some commentators have said the impact may be more strongly felt since alternative firearms are not as easily obtainable.<ref name="AutoSQ-84" /> Officials in the United Kingdom have noted that producing a 3D-printed gun would be illegal under their gun control laws.<ref name="AutoSQ-85" /> [[Europol]] stated that criminals have access to other sources of weapons but noted that as technology improves, the risks of an effect would increase.<ref name="AutoSQ-86" /><ref name="AutoSQ-87" />

=== Aerospace regulation ===
In the United States, the FAA has anticipated a desire to use additive manufacturing techniques and has been considering how best to regulate this process.<ref>{{Cite web|url=https://spacenews.com/faa-prepares-guidance-for-wave-of-3d-printed-aerospace-parts/|title=FAA prepares guidance for wave of 3D-printed aerospace parts|date=20 October 2017|website=SpaceNews.com|access-date=23 August 2019|archive-date=6 July 2024|archive-url=https://web.archive.org/web/20240706231418/https://spacenews.com/faa-prepares-guidance-for-wave-of-3d-printed-aerospace-parts/|url-status=live}}</ref> The FAA has jurisdiction over such fabrication because all aircraft parts must be made under FAA production approval or under other FAA regulatory categories.<ref>{{cite web|url=https://www.ecfr.gov/cgi-bin/text-idx?rgn=div5;node=14:1.0.1.3.9#se14.1.21_19|title=eCFR – Code of Federal Regulations|website=ecfr.gov|access-date=4 August 2018|archive-date=4 August 2018|archive-url=https://web.archive.org/web/20180804170301/https://www.ecfr.gov/cgi-bin/text-idx?rgn=div5;node=14:1.0.1.3.9#se14.1.21_19}}</ref> In December 2016, the FAA approved the production of a 3D-printed fuel nozzle for the GE LEAP engine.<ref>{{Cite web|url=https://3dprintingindustry.com/news/faa-launch-eight-year-additive-manufacturing-road-map-123108/|title=FAA to launch eight-year additive manufacturing road map|date=21 October 2017|website=3D Printing Industry|access-date=18 January 2018|archive-date=19 January 2018|archive-url=https://web.archive.org/web/20180119001141/https://3dprintingindustry.com/news/faa-launch-eight-year-additive-manufacturing-road-map-123108/|url-status=live}}</ref> Aviation attorney Jason Dickstein has suggested that additive manufacturing is merely a production method, and should be regulated like any other production method.<ref name="arsa.org">{{Cite web|url=http://arsa.org/news-media/newsletters/2017-edition-4/|title=2017 – Edition 4 – May 5, 2017 – ARSA|website=arsa.org|access-date=18 January 2018|archive-date=19 January 2018|archive-url=https://web.archive.org/web/20180119120232/http://arsa.org/news-media/newsletters/2017-edition-4/|url-status=live}}</ref><ref>{{Cite web|url=https://www.mro-network.com/safety-regulatory/embracing-drones-and-3d-printing-regulatory-framework|title=Embracing Drones and 3D Printing in the Regulatory Framework|date=10 January 2018|website=MRO Network|access-date=23 August 2019|archive-date=23 August 2019|archive-url=https://web.archive.org/web/20190823030142/https://www.mro-network.com/safety-regulatory/embracing-drones-and-3d-printing-regulatory-framework|url-status=live}}</ref> He has suggested that the FAA's focus should be on guidance to explain compliance, rather than on changing the existing rules, and that existing regulations and guidance permit a company "to develop a robust quality system that adequately reflects regulatory needs for quality assurance".<ref name="arsa.org" />

=== Quality assurance ===
In 2021, first standards were issued, e.g. ASTM ISO/ASTM52900-21 Additive manufacturing general principles, fundamentals and vocabulary, and the above mentioned ISO/ASTM52900-15.<ref name=":6" /><ref name=":7" /> In 2023, the ISO/ASTM 52920:2023<ref>{{Cite web |title=ISO/ASTM 52920:2023(en) Additive manufacturing — Qualification principles — Requirements for industrial additive manufacturing processes and production sites |url=https://www.iso.org/obp/ui/en/#iso:std:iso-astm:52920:ed-1:v1:en |access-date=2025-03-06 |website=www.iso.org}}</ref> defined the requirements for industrial additive manufacturing processes and production sites using additive manufacturing to ensure reěuired quality level. Aforetime in Germany there was a draft of DIN norm issued, DIN SPEC 17071:2019.

== Health and safety ==
{{Main|Health and safety hazards of 3D printing}}
{{See also|Health and safety hazards of nanomaterials}}
Polymer feedstock materials can release [[ultrafine particle]]s and [[volatile organic compound]]s (VOCs) if sufficiently heated, which in combination have been associated with adverse [[Respiratory disease|respiratory]] and [[Cardiovascular disease|cardiovascular]] health effects.  In addition, temperatures of 190&nbsp;°C to 260&nbsp;°C are typically reached by an [[Fused filament fabrication|FFF]] extrusion nozzle, which can cause skin burns.  [[Stereolithography|Vat photopolymerization stereolithography]] printers use high-powered [[laser]]s that present a skin and eye hazard, although they are considered nonhazardous during printing because the laser is enclosed within the printing chamber.<ref name=":5" />

3D printers also contain many moving parts that include [[stepper motor]]s, pulleys, threaded rods, carriages, and small fans, which generally do not have enough power to cause serious injuries but can still trap a user's finger, long hair, or loose clothing.  Most desktop FFF 3D printers do not have any added electrical safety features beyond regular internal fuses or external transformers, although the voltages in the exposed parts of 3D printers usually do not exceed 12V to 24V, which is generally considered safe.<ref name=":5">{{Cite report |url=https://www.cdc.gov/niosh/docs/2024-103/ |title=Approaches to safe 3D printing: a guide for makerspace users, schools, libraries, and small businesses |date=2023-11-01 |publisher=U.S. National Institute for Occupational Safety and Health |doi=10.26616/nioshpub2024103 |language=en|url-access=subscription }}{{source-attribution}}</ref>[[File:NIOSH Scientists Investigating Pollution From Office Equipment.webm|thumb|A video on research done on printer emissions]]

Research on the health and safety concerns of 3D printing is new and in development due to the recent proliferation of 3D printing devices. In 2017, the [[European Agency for Safety and Health at Work]] published a discussion paper on the processes and materials involved in 3D printing, the potential implications of this technology for occupational safety and health and avenues for controlling potential hazards.<ref>{{Cite web|url=https://osha.europa.eu/en/highlights/3d-printing-and-monitoring-workers-new-industrial-revolution|title=3D Printing and monitoring of workers: a new industrial revolution?|date=7 June 2017|website=osha.europa.eu|access-date=31 October 2017|archive-date=24 September 2017|archive-url=https://web.archive.org/web/20170924151423/https://osha.europa.eu/en/highlights/3d-printing-and-monitoring-workers-new-industrial-revolution|url-status=live}}</ref>

[[Noise|Noise level]] is measured in [[decibel]]s (dB), and can vary greatly in home printers from 15&nbsp;dB to 75&nbsp;dB.<ref name="3dprintknowledge-1">{{Cite web|url=https://3dprintknowledge.com/how-loud-are-3d-printers-and-how-can-i-reduce-their-noise/|title=How Loud Are 3D Printers and Making Them Quiet.|date=21 July 2020|access-date=12 November 2022|archive-date=12 November 2022|archive-url=https://web.archive.org/web/20221112125814/https://3dprintknowledge.com/how-loud-are-3d-printers-and-how-can-i-reduce-their-noise/|url-status=live}}</ref> Some main sources of noise in filament printers are fans, motors and bearings, while in resin printers the fans usually are responsible for most of the noise.<ref name="3dprintknowledge-1"/> Some methods for dampening the noise from a printer may be to install [[vibration isolation]], use larger diameter [[Computer fan|fans]], perform regular maintenance and lubrication, or use a [[soundproofing]] enclosure.<ref name="3dprintknowledge-1"/>

== Impact ==
Additive manufacturing, starting with today's infancy period, requires manufacturing firms to be flexible, [[continuous improvement process|ever-improving]] users of all available technologies to remain competitive. Advocates of [[additive manufacturing]] also predict that this arc of technological development will counter [[globalization]], as end users will do much of their own manufacturing rather than engage in trade to buy products from other people and corporations.<ref name="3D opp" /> The real integration of the newer additive technologies into commercial production, however, is more a matter of complementing traditional subtractive methods rather than displacing them entirely.<ref name="Albert_2011-02_MMS_column" />

The [[futurologist]] [[Jeremy Rifkin]]<ref>{{cite web|url=http://www.thethirdindustrialrevolution.com/|title=Jeremy Rifkin and The Third Industrial Revolution Home Page|publisher=The third industrial revolution.com|access-date=4 January 2016|archive-date=25 February 2017|archive-url=https://web.archive.org/web/20170225091019/http://thethirdindustrialrevolution.com/}}</ref> claimed that 3D printing signals the beginning of a [[third industrial revolution]],<ref>{{cite news|url=http://www.economist.com/node/21552901|title=A third industrial revolution|date=21 April 2012|newspaper=The Economist|access-date=4 January 2016|archive-date=16 June 2018|archive-url=https://web.archive.org/web/20180616180403/http://www.economist.com/node/21552901|url-status=live}}</ref> succeeding the [[production line]] assembly that dominated manufacturing starting in the late 19th century.

=== Social change ===
[[File:3D Printing-skylt.jpg|thumb|Street sign in [[Windhoek]], [[Namibia]], advertising 3D printing, July 2018]]
Since the 1950s, a number of writers and social commentators have speculated in some depth about the social and cultural changes that might result from the advent of commercially affordable additive manufacturing technology.<ref name="AutoSQ-104" /> In recent years, 3D printing has created a significant impact in the humanitarian and development sector. Its potential to facilitate distributed manufacturing is resulting in supply chain and logistics benefits, by reducing the need for transportation, warehousing and wastage. Furthermore, social and economic development is being advanced through the creation of local production economies.<ref name="auto" />

Others have suggested that as more and more 3D printers start to enter people's homes, the conventional relationship between the home and the workplace might get further eroded.<ref name="AutoSQ-105" /> Likewise, it has also been suggested that, as it becomes easier for businesses to transmit designs for new objects around the globe, so the need for high-speed freight services might also become less.<ref name="AutoSQ-106" /> Finally, given the ease with which certain objects can now be replicated, it remains to be seen whether changes will be made to current copyright legislation so as to protect intellectual property rights with the new technology widely available.

Some call attention to the conjunction of [[commons-based peer production]] with 3D printing and other low-cost manufacturing techniques.<ref name="triple-c.at" /><ref name="AutoSQ-111" /><ref name="AutoSQ-112" /> The self-reinforced fantasy of a system of eternal growth can be overcome with the development of economies of scope, and here, society can play an important role contributing to the raising of the whole productive structure to a higher plateau of more sustainable and customized productivity.<ref name="triple-c.at" /> Further, it is true that many issues, problems, and threats arise due to the democratization of the means of production, and especially regarding the physical ones.<ref name="triple-c.at" /> For instance, the recyclability of advanced nanomaterials is still questioned; weapons manufacturing could become easier; not to mention the implications for counterfeiting<ref name="AutoSQ-113" /> and on intellectual property.<ref name="AutoSQ-114" /> It might be maintained that in contrast to the industrial paradigm whose competitive dynamics were about economies of scale, [[commons-based peer production]] 3D printing could develop economies of scope. While the advantages of scale rest on cheap global transportation, the economies of scope share infrastructure costs (intangible and tangible productive resources), taking advantage of the capabilities of the fabrication tools.<ref name="triple-c.at" /> And following Neil Gershenfeld<ref name="AutoSQ-115" /> in that "some of the least developed parts of the world need some of the most advanced technologies", commons-based peer production and 3D printing may offer the necessary tools for thinking globally but acting locally in response to certain needs.

[[Larry Summers]] wrote about the "devastating consequences" of 3D printing and other technologies (robots, artificial intelligence, etc.) for those who perform routine tasks. In his view, "already there are more American men on disability insurance than doing production work in manufacturing. And the trends are all in the wrong direction, particularly for the less skilled, as the capacity of capital embodying artificial intelligence to replace white-collar as well as blue-collar work will increase rapidly in the years ahead." Summers recommends more vigorous cooperative efforts to address the "myriad devices" (e.g., tax havens, bank secrecy, money laundering, and regulatory arbitrage) enabling the holders of great wealth to "a paying" income and estate taxes, and to make it more difficult to accumulate great fortunes without requiring "great social contributions" in return, including: more vigorous enforcement of anti-monopoly laws, reductions in "excessive" protection for intellectual property, greater encouragement of profit-sharing schemes that may benefit workers and give them a stake in wealth accumulation, strengthening of collective bargaining arrangements, improvements in corporate governance, strengthening of financial regulation to eliminate subsidies to financial activity, easing of land-use restrictions that may cause the real estate of the rich to keep rising in value, better training for young people and retraining for displaced workers, and increased public and private investment in infrastructure development—e.g., in energy production and transportation.<ref name="AutoSQ-116" />

[[Michael Spence]] wrote that "Now comes a ... powerful, wave of digital technology that is replacing labor in increasingly complex tasks. This process of labor substitution and [[disintermediation]] has been underway for some time in service sectors—think of ATMs, online banking, enterprise resource planning, customer relationship management, mobile payment systems, and much more. This revolution is spreading to the production of goods, where robots and 3D printing are displacing labor." In his view, the vast majority of the cost of digital technologies comes at the start, in the design of hardware (e.g. 3D printers) and, more importantly, in creating the software that enables machines to carry out various tasks. "Once this is achieved, the marginal cost of the hardware is relatively low (and declines as scale rises), and the marginal cost of replicating the software is essentially zero. With a huge potential global market to amortize the upfront fixed costs of design and testing, the incentives to invest [in digital technologies] are compelling."<ref name="AutoSQ-117" />

Spence believes that, unlike prior digital technologies, which drove firms to deploy underutilized pools of valuable labor around the world, the motivating force in the current wave of digital technologies "is cost reduction via the replacement of labor". For example, as the cost of 3D printing technology declines, it is "easy to imagine" that production may become "extremely" local and customized. Moreover, production may occur in response to actual demand, not anticipated or forecast demand. Spence believes that labor, no matter how inexpensive, will become a less important asset for growth and employment expansion, with labor-intensive, process-oriented manufacturing becoming less effective, and that re-localization will appear in both developed and developing countries. In his view, production will not disappear, but it will be less labor-intensive, and all countries will eventually need to rebuild their growth models around digital technologies and the human capital supporting their deployment and expansion. Spence writes that "the world we are entering is one in which the most powerful global flows will be ideas and digital capital, not goods, services, and traditional capital. Adapting to this will require shifts in mindsets, policies, investments (especially in human capital), and quite possibly models of employment and distribution."<ref name="AutoSQ-117" />

[[Naomi Wu]] regards the usage of 3D printing in the Chinese classroom (where rote memorization is standard) to teach design principles and creativity as the most exciting recent development of the technology, and more generally regards 3D printing as being the next [[desktop publishing]] revolution.<ref name="3D Printing in the Chinese Classroom">{{Cite web |url=https://womenin3dprinting.com/2017/11/29/naomi-wu-my-visibility-allows-me-to-direct-more-attention-to-important-issues-and-other-deserving-women/ |title=Naomi Wu – "My visibility allows me to direct more attention to important issues and other deserving women" |last=Andre |first=Helene |date=29 November 2017 |website=Women in 3D Printing |access-date=3 December 2017 |archive-url=https://web.archive.org/web/20171204171133/https://womenin3dprinting.com/2017/11/29/naomi-wu-my-visibility-allows-me-to-direct-more-attention-to-important-issues-and-other-deserving-women/ |archive-date=4 December 2017 }}</ref>

A printer was donated to the [[Juan Fernandez Women's Group]] in 2024, to support women in the remote community to be able to create parts to fix broken equipment, without having to wait for a ship to import the needed compenents.<ref>{{Cite web |last=OnAllBands |date=2024-03-15 |title=DX Engineering-Sponsored CB0ZA Juan Fernandez Islands DXpedition a Big Success |url=https://www.onallbands.com/dx-engineering-sponsored-cb0za-juan-fernandez-islands-dxpedition-a-big-success/ |access-date=2024-10-07 |website=OnAllBands |language=en-US}}</ref>

=== Environmental change ===

The growth of additive manufacturing could have a large impact on the environment. Traditional subtractive manufacturing methods such as [[CNC milling]] create products by cutting away material from a larger block. In contrast, additive manufacturing creates products layer-by layer, using the minimum required materials to create the product.<ref name=":2">{{Cite journal |last1=Mohd Yusuf |first1=Shahir |last2=Cutler |first2=Samuel |last3=Gao |first3=Nong |date=29 November 2019 |title=Review: The Impact of Metal Additive Manufacturing on the Aerospace Industry |journal=Metals |language=en |volume=9 |issue=12 |pages=1286 |doi=10.3390/met9121286 |doi-access=free |issn=2075-4701}}</ref> This has the benefit of reducing material waste, which further contributes to energy savings by avoiding raw material production.<ref>{{Cite journal |last1=Ma |first1=Junfeng |last2=Harstvedt |first2=James D. |last3=Dunaway |first3=Daniel |last4=Bian |first4=Linkan |last5=Jaradat |first5=Raed |date=2018-08-10 |title=An exploratory investigation of Additively Manufactured Product life cycle sustainability assessment |url=https://linkinghub.elsevier.com/retrieve/pii/S0959652618312915 |journal=Journal of Cleaner Production |volume=192 |pages=55–70 |doi=10.1016/j.jclepro.2018.04.249 |bibcode=2018JCPro.192...55M |issn=0959-6526|url-access=subscription }}</ref><ref name="Is 3D Printing the Future of Sustainable Manufacturing?">{{Cite web |url=https://www.environmentalleader.com/2015/11/is-3d-printing-the-future-of-sustainable-manufacturing/ |title=Is 3D Printing the Future of Sustainable Manufacturing? |last=Lyons Hardcastle |first=Jessica |date=24 November 2015 |website=Environmental Leader |access-date=21 January 2019 |archive-date=22 January 2019 |archive-url=https://web.archive.org/web/20190122044423/https://www.environmentalleader.com/2015/11/is-3d-printing-the-future-of-sustainable-manufacturing/ |url-status=live }}</ref>

[[Life-cycle assessment]] of additive manufacturing has estimated that adopting the technology could further lower carbon dioxide emissions since 3D printing creates localized production, thus reducing the need to transport products and the emissions associated.<ref>{{cite journal |last1=Gelber |first1=Malte |last2=Uiterkamp |first2=Anton J.M. Schoot |last3=Visser |first3=Cindy |date=October 2015 |title=A Global Sustainability Perspective of 3D Printing Technologies |journal=Energy Policy |volume=74 |issue=1 |pages=158–167 |doi=10.1016/j.enpol.2014.08.033}}</ref> AM could also allow consumers to create their own replacement parts to fix purchased products to extend the lifespan of purchased products.<ref>{{Cite journal |last=Attaran |first=Mohsen |date=2017-09-01 |title=The rise of 3-D printing: The advantages of additive manufacturing over traditional manufacturing |url=https://www.sciencedirect.com/science/article/abs/pii/S0007681317300897 |journal=Business Horizons |volume=60 |issue=5 |pages=677–688 |doi=10.1016/j.bushor.2017.05.011 |issn=0007-6813|url-access=subscription }}</ref>

By making only the bare structural necessities of products, additive manufacturing also has the potential to make profound contributions to [[lightweighting]].<ref name=":2" /> The use of these lightweight components would allow for reductions in the energy consumption and [[greenhouse gas emissions]] of vehicles and other forms of transportation.<ref name="Lightweighting with Lattices">{{Cite web |url=https://www.additivemanufacturing.media/blog/post/lightweighting-with-lattices(2) |title=Lightweighting with Lattices |last=Simpson |first=Timothy W. |date=31 January 2018 |website=Additive Manufacturing |access-date=21 January 2019 |archive-date=22 January 2019 |archive-url=https://web.archive.org/web/20190122044305/https://www.additivemanufacturing.media/blog/post/lightweighting-with-lattices(2) |url-status=live }}</ref> A case study on an airplane component made using additive manufacturing, for example, found that the use of the component saves 63% of relevant energy and carbon dioxide emissions over the course of the product's lifetime.<ref>{{Cite web |url=http://www.econolyst.co.uk/resources/documents/files/Presentation___2012___AM_and_carbon_footprint.pdf |title=Example of Econolyst Research-Understanding the Benefits of AM on CO2 |last=Reeves |first=P. |date=2012 |website=The Econolyst |access-date=21 January 2019 |archive-date=19 August 2019 |archive-url=https://web.archive.org/web/20190819102646/http://www.econolyst.co.uk/resources/documents/files/Presentation___2012___AM_and_carbon_footprint.pdf |url-status=live }}</ref>

However, the adoption of additive manufacturing also has environmental disadvantages. Firstly, AM has a high energy consumption compared to traditional processes. This is due to its use of processes such as lasers and high temperatures for product creation.<ref>{{Cite journal |last1=Liu |first1=Zhichao |last2=Jiang |first2=Qiuhong |last3=Ning |first3=Fuda |last4=Kim |first4=Hoyeol |last5=Cong |first5=Weilong |last6=Xu |first6=Changxue |last7=Zhang |first7=Hong-chao |date=10 October 2018 |title=Investigation of Energy Requirements and Environmental Performance for Additive Manufacturing Processes |journal=Sustainability |language=en |volume=10 |issue=10 |pages=3606 |doi=10.3390/su10103606 |doi-access=free |bibcode=2018Sust...10.3606L |issn=2071-1050|hdl=2346/92286 |hdl-access=free }}</ref> Secondly, despite additive manufacturing reducing up to 90% of waste compared to subtractive manufacturing, AM can generate waste that is non-recyclable.<ref>{{Cite news |date=21 April 2012 |title=A third industrial revolution |url=https://www.economist.com/special-report/2012/04/21/a-third-industrial-revolution |access-date=2024-10-23 |newspaper=The Economist |issn=0013-0613}}</ref> For example, there are issues with the recyclability of materials in metal AM as some highly regulated industries such as [[Aerospace engineering|aerospace]] often insist on using virgin powder in the creation of safety critical components.<ref name=":2" /> Additive manufacturing has not yet reached its theoretical [[material efficiency]] potential of 97%, but it may get closer as the technology continues to increase productivity.<ref>{{cite journal |last1=Peng |first1=Tao |last2=Kellens |first2=Karel |last3=Tang |first3=Renzhong |last4=Chen |first4=Chao |last5=Chen |first5=Gang |date=May 2018 |title=Sustainability of additive manufacturing: An overview on its energy demand and environmental impact |journal=Additive Manufacturing |volume=21 |issue=1 |pages=694–704 |doi=10.1016/j.addma.2018.04.022
 }}</ref>

Despite the drawbacks, research and industry are making further strides to support AM's sustainability. Some large FDM printers that melt [[high-density polyethylene]] (HDPE) pellets may also accept sufficiently clean recycled material such as chipped milk bottles. In addition, these printers can use shredded material from faulty builds or unsuccessful prototype versions, thus reducing overall project wastage and materials handling and storage. The concept has been explored in the [[RecycleBot]].<ref>{{Cite journal |last1=Daniele |first1=Rigotti |last2=Armoni |first2=Davide |last3=Dul |first3=Sithiprumnea |last4=Alessandro |first4=Pegoretti |date=4 August 2023 |title=From Nautical Waste to Additive Manufacturing: Sustainable Recycling of High-Density Polyethylene for 3D Printing Applications |journal=Journal of Composites Science |language=en |volume=7 |issue=8 |pages=320 |doi=10.3390/jcs7080320 |doi-access=free |issn=2504-477X|hdl=11572/399272 |hdl-access=free }}</ref> There are also industrial efforts to produce metal powder from recycled metals.<ref>{{Cite web |last=McMahon |first=Martin |date=2023 |title=Metal powders in Additive Manufacturing: An exploration of sustainable production, usage and recycling |url=https://www.metal-am.com/articles/metal-powders-in-additive-manufacturing-an-exploration-of-sustainable-production-usage-and-recycling/ |website=Metal AM}}</ref>

== See also ==
{{Portal|Manufacturing}}
{{div col|colwidth=22em}}
* [[3D bioprinting]]
* [[3D food printing]]
* [[3D Manufacturing Format]]
* [[3D printing marketplace]]
* [[3D printing speed]]
* [[3D printing in India]]
* [[AstroPrint]]
* [[Bubblegram]]
* [[Cloud manufacturing]]
* [[Comparison of 3D printers]]
* [[Computer numeric control]]
* [[Delta robot]]
* [[Fraunhofer Competence Field Additive Manufacturing]]
* [[Fusion3]]
* [[Laser cutting]]
* [[Limbitless Solutions]]
* [[List of 3D printer manufacturers]]
* [[List of 3D printing software]]
* [[List of common 3D test models]]
* [[List of emerging technologies]]
* [[List of notable 3D printed weapons and parts]]
* [[Magnetically assisted slip casting]]
* [[MakerBot Industries]]
* [[Milling center]]
* [[Organ-on-a-chip]]
* [[Robocasting]]
* [[Self-replicating machine]]
* [[Ultimaker]]
* [[Volumetric printing]]
{{div col end}}

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<ref name="AutoSQ-111">{{cite journal |doi=10.1016/j.tele.2013.09.006 |title=Commons-based peer production and digital fabrication: The case of a Rep ''Rap''-based, Lego-built 3D printing-milling machine |journal=Telematics and Informatics |volume=31 |issue=3 |pages=434–43 |year=2014 |last1=Kostakis |first1=Vasilis |last2=Papachristou |first2=Marios |s2cid=2297267 }}</ref>
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<ref name="AutoSQ-113">{{Cite web|url=https://www.atlanticcouncil.org/publications/reports/could-3d-printing-change-the-world|title=Could 3D Printing Change the World?|author=Thomas Campbell|author2=Christopher Williams|author3=Olga Ivanova|author4=Banning Garrett|website=Atlantic Council|language=en-gb|access-date=23 August 2019|date=17 October 2011|archive-date=23 August 2019|archive-url=https://web.archive.org/web/20190823103004/https://www.atlanticcouncil.org/publications/reports/could-3d-printing-change-the-world|url-status=live}}</ref>
<ref name="AutoSQ-114">{{Cite journal|last1=Haufe|first1=Patrick|last2=Bowyer|first2=Adrian|last3=Bradshaw|first3=Simon|date=2010|title=The intellectual property implications of low-cost 3D printing|url=https://researchportal.bath.ac.uk/en/publications/the-intellectual-property-implications-of-low-cost-3d-printing|journal=SCRIPTed|language=en|volume=7|issue=1|pages=5–31|issn=1744-2567}}</ref>
<ref name="AutoSQ-115">{{cite book|last=Gershenfeld|first=Neil|title=Fab: The Coming Revolution on Your Desktop—from Personal Computers to Personal Fabrication|url=https://books.google.com/books?id=Zw0j50HDwYUC&pg=PA13|date=2008|publisher=Basic Books|isbn=978-0-7867-2204-4|pages=13–14|access-date=23 August 2019|archive-date=6 July 2024|archive-url=https://web.archive.org/web/20240706231419/https://books.google.com/books?id=Zw0j50HDwYUC&pg=PA13#v=onepage&q&f=false|url-status=live}}</ref>
<ref name="AutoSQ-116">{{Cite web|url=https://democracyjournal.org/magazine/33/the-inequality-puzzle/|title=The Inequality Puzzle|date=14 May 2014|website=Democracy Journal|access-date=23 August 2019|archive-date=23 August 2019|archive-url=https://web.archive.org/web/20190823030136/https://democracyjournal.org/magazine/33/the-inequality-puzzle/|url-status=live}}</ref>
<ref name="AutoSQ-117">{{Cite web|url=https://www.project-syndicate.org/commentary/michael-spence-describes-an-era-in-which-developing-countries-can-no-longer-rely-on-vast-numbers-of-cheap-workers|title=Labor's Digital Displacement {{pipe}} by Michael Spence|first=Michael|last=Spence|date=22 May 2014|website=Project Syndicate|access-date=23 August 2019|archive-date=8 March 2022|archive-url=https://web.archive.org/web/20220308163009/https://www.project-syndicate.org/commentary/michael-spence-describes-an-era-in-which-developing-countries-can-no-longer-rely-on-vast-numbers-of-cheap-workers|url-status=live}}</ref>
<ref name="Satyanarayana">{{cite journal | last1=Satyanarayana | first1=B. | last2=Prakash | first2=Kode Jaya | title=Component Replication Using 3D Printing Technology | journal=Procedia Materials Science | publisher=Elsevier BV | volume=10 | year=2015 | issn=2211-8128 | doi=10.1016/j.mspro.2015.06.049 | pages=263–269| doi-access=free }}</ref>
}}

== Further reading ==
{{Scholia}}
* {{Cite book|title=Fabricated: the new world of 3D printing|last=Lipson |first=Hod|author2=Kurman, Melba |isbn=978-1-118-35063-8 |location=Indianapolis, Indiana |publisher=John Wiley & Sons |oclc=806199735|date=2013}}
* {{cite SSRN |last=Tran |first=Jasper |year=2017 |title=Reconstructionism, IP and 3D Printing |ssrn=2842345}}
* {{cite journal |last=Tran |first=Jasper |year=2016 |title=Press Clause and 3D Printing |journal=Northwestern Journal of Technology and Intellectual Property |volume=14 |pages=75–80 |ssrn=2614606}}
* {{cite journal |last=Tran |first=Jasper |year=2016 |title=3D-Printed Food |journal=Minnesota Journal of Law, Science and Technology |volume=17 |pages=855–80 |ssrn=2710071}}
* {{cite journal |last=Tran |first=Jasper |year=2015 |title=To Bioprint or Not to Bioprint |journal=North Carolina Journal of Law and Technology |volume=17 |pages=123–78 |ssrn=2562952}}
* {{cite journal |last=Tran |first=Jasper |year=2015 |title=Patenting Bioprinting |journal=Harvard Journal of Law and Technology Digest |ssrn=2603693}}
* {{cite journal |last=Tran |first=Jasper |year=2015 |title=The Law and 3D Printing |journal=John Marshall Journal of Information Technology and Privacy Law |volume=31 |pages=505–20 |url=http://repository.jmls.edu/jitpl/vol31/iss4/2/}}
* {{cite journal |last=Lindenfeld |first=Eric |display-authors=etal|year=2015 |title= Strict Liability and 3D-Printed Medical Devices |journal=Yale Journal of Law and Technology |ssrn=2697245}}
* {{cite book |doi=10.1007/978-3-319-31686-4_9 |chapter=Materializing Digital Futures |title=The Decentralized and Networked Future of Value Creation |pages=163–78 |series=Progress in IS |year=2016 |last1=Dickel |first1=Sascha |last2=Schrape |first2=Jan-Felix |isbn=978-3-319-31684-0 |s2cid=148483485 }}
* {{cite web|title=Results of Make Magazine's 2015 3D Printer Shootout|url=https://docs.google.com/spreadsheets/d/1EKsDga2PVD_H9HI2MJbPXCey6bYFEIWErOsAHKHZ3GU/edit#gid=1210667708|access-date=1 June 2015}}
* {{cite web|title=Evaluation Protocol for Make Magazine's 2015 3D Printer Shootout|url=http://makezine.com/2014/11/07/how-to-evaluate-the-2015-make-3dp-test-probes/|publisher=makezine.com|access-date=1 June 2015}}
* {{cite web|title=Heat Beds in 3D Printing – Advantages and Equipment|url=http://bootsindustries.com/portfolio-item/heat-bed-3d-printing/|website=Boots Industries|access-date=7 September 2015}}
* {{cite journal |last1=Stephens |first1=B. |last2=Azimi |first2=P. |last3=El Orch |first3=Z. |last4=Ramos |first4=T. |title=Ultrafine particle emissions from desktop 3D printers |doi=10.1016/j.atmosenv.2013.06.050 |journal=Atmospheric Environment |volume=79 |pages=334–339 |year=2013|bibcode=2013AtmEn..79..334S |doi-access=free }}
* {{cite journal |last=Easton |first=Thomas A. |date=November 2008|title=The 3D Trainwreck: How 3D Printing Will Shake Up Manufacturing |journal=[[Analog Science Fiction and Fact|Analog]] |volume=128 |issue=11 |pages=50–63 }}
* Wright, Paul K. (2001). ''21st Century Manufacturing''. New Jersey: Prentice-Hall Inc.
* "3D printing: a new industrial revolution – Safety and health at work – EU-OSHA". ''osha.europa.eu''. Retrieved 28 July 2017.

== External links ==
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