3D printing is the common term for additive manufacturing (AM) technologies . This process is "additive" in the sense that it creates a three-dimensional (3D) object by layering polymer material, building up the object from scratch rather than removing material as is done in sculpting and milling. 3D printers possess the ability to take digital model data, created using computer-aided design (CAD), a computer-aided manufacturing (CAM) program, or an Additive Manufacturing File (AMF), and transform it into a physical object. 3D printing allows for mass customization, energy-efficiency, and reduced time and financial costs in manufacturing. There are a variety of ethical concerns with this technology, including difficulty protecting intellectual property, misuse of the technology for criminal purposes, elimination of jobs, and human enhancement. Although 3D printing is not yet widely used, the technology has been extended into 4D printing, which allows printed materials to autonomously reshape over time.
- 1 History
- 2 Usage
- 3 Benefits
- 4 Ethical Concerns
- 5 Continuing Advancements
- 6 References
In the 1980s, 3D printing was more commonly referred to as rapid prototyping (RP) technologies. In 1981, Dr. Hideo Kodama of Nagoya Municipal Industrial Research Institute filed for the first patent application for RP technology after inventing two AM construction methods of a 3D plastic model. 
In 1986, Charles "Chuck" Hull issued a patent for stereolithography apparatus (SLA). This would later be known as one of the earlier 3D printers. Stereolithography works by exposing a vat of liquid photopolymer, an acrylic-based material, with a UV laser beam. The UV laser beam traces the first layer of an object onto the surface of the liquid, and as that portion is exposed to the UV beam, it hardens into plastic. This process is continued on for many more layers until the whole object is printed.  Dr. Kodama founded the process, but Hull played a significant role in the design of STereoLithography (STL) file format that most 3D printing software can interpret to begin producing material.
AM processes also include Selective laser sintering (SLS) during which lasers meld layers of powdered material together to produce a solid object, as well as multi-jet modeling (MJM), which also builds up an object by using an inkjet printhead to spray a binder solution that will glue together layers of powder.
In 2005, the RepRap Project was founded in England, and marked the advent of an open-source community working to make 3D printing technologies available for everyone; and so, all designs were released under the GNU General Public License, a free software license.  Following the RepRap project came the BfB RapMan 3D printer, the first 3D printer intended for commercial use.  Shortly after, MakerBot was founded in 2009. MakerBot sold do-it-yourself styled kits, putting onto the market the possibility for consumers of all types to access and learn this technology to produce their own products and designs. 
3D printing can be used to create almost any kind of static product model and prototype - from jewelry to tools to a full-sized house. The automotive industry as well as the aviation sector can use 3D printing to make prototypes of vehicle parts. Architects can use 3D printing to create models of their projects. The medical field can utilize 3D printing to produce prosthetics and artificial teeth for their patients, or even replicas of organs to help prepare for surgery.  In Sudan, Not Impossible labs created Project Daniel, which worked to print prosthetic arms for Daniel, a teen who had lost his arms as a result of violence.  3D printing can also be used in the engineering field to produce printed electronics, allowing layered circuitry and devices to be printed on flexible material, or in the culinary field to help with food preparation.
3D printing is growing increasingly popular. It is used in several businesses and is moving towards wider personal consumer use in households 
A slicer is a software that translates 3d object files into G-code, numerical control instructions for a printer.  A slicer works by segmenting a given model into many horizontal layers, where each layer is translated into movement instructions. A user is able to tune their printer's settings through a slicer. Layer height, number of walls, wall thickness, infill, and print speed can all be changed through the slicer. The resulting quality of a printed object can be significantly improved through slicer settings. Popular slicers include Cura, Slic3r  and Simplify3D.
3D printing, otherwise known as Additive Manufacturing, has revolutionized manufacturing, creating benefits at the industrial, local, and personal level that can't be accomplished with only the traditional methods of manufacturing.
Manufacturers using 3D printing technology enjoy significant increases in the pace of prototyping that is possible. This increase in prototyping turnaround can lead to a more efficient iterative design process and may yield cost savings due to less waste when manufacturing products with tight fit and design tolerances.
3D printing grants the ability for mass customization; people can tailor their products to individual needs and constraints in larger numbers at no significant additional process cost. It also eliminates the limitation of complexity for designers and engineers; they are free to let their creativity flow and develop complex products that may even end up being lighter and stronger than past prototypes.
On a local level, 3D printing is acknowledged as a technology that is energy-efficient. It can use up to 90% of the standard material, creating little waste, and as a byproduct of producing lighter and stronger materials, it also leaves a smaller carbon footprint than that of manufactured products made from traditional methods. 
At an industrial level, 3D printing can reduce financial and time costs for tool production. Products can be manufactured in high volumes while also maintaining uniformity. Products can also be designed in such a way that avoids difficult assembly processes and requirements, decreasing labor and costs there as well. 
On top of the benefits 3D printing provides for industrial and personal venture, use has also been found for this technology in the field of medicine. A 3D printer can be used to fabricate a variety of parts and structures based on the materials used in the printing process, when stem cells or some other highly malleable organic material is used, the printing of organs becomes possible. Sources claim that by 2021, the bioprinting industry may be worth upwards of 1.3 billion dollars.  However; recent developments in alternative methods in organ printing and the successful printing of working liver cells have given rise to hopes of reducing the organ shortage in the near future. 
Intellectual Property Rights
3D printing allows for easy replication and reproduction making it difficult to track copyright legislation and protect intellectual property rights. Protection of intellectual property is one of four main ethical issues stated by Richard Mason as the information age evolves. In addition to the difficulties with intellectual property, 3D printing adds another level difficulty to property rights; an object printed from a 3D printer could be considered the property of the designer of the CAD drawings or the owner of the 3D printer. This relates back to the issue of intellectual property in cyberspace mentioned by Mason. Just as the bandwidth is a conduit through which information passes, the 3D printer is the avenue through which the information or CAD drawings are transferred. It is an ethical concern that needs to be addressed as the 3D printing world continues to take manufacturing by storm. Researchers at Gartner Inc. even analyzed the economic impact of the infringement of intellectual property rights on 3D printing. It predicted the global loss of at least $100 billion per year in intellectual property by 2018. 
As accessibility to 3D printing technology continues to grow, and consumers currently hold the freedom to print any design they desire, there remains a potential for misuse of this technology. It's possible for an individual to produce 3D printed firearms, regardless of gun control and regulation laws. In 2013 congress voted to uphold that plastic firearms must continue to include a strip of metal in their production to be detected by metal detectors. The main discussion point revolves around where the responsibility falls should someone be killed from a 3D printed gun. Philip Brey, a philosopher in computer ethics, describes that within technology are embedded values that may not necessarily be the intent of the designer. So, in this case, we must recognize as a society to begin to look at 3D printing as a moral agent and lay groundwork for moral responsibility. The designer of the 3D printer never had the intent to kill others, but they technically allowed for the gun to be printed. As technology continues to advance seemingly morally opaque systems just as a 3D printer are becoming visibly more problematic in the wake of multiple mass shootings. The current lack of regulation on 3D printing technologies allows for potential misuse by users made possible through this technology.
The benefits of 3D printing on an industrial level also come with possible consequences. With the speed and ease that the technology provides in manufacturing products in bulk and the ability to reduce labor costs, it could also put millions of manufacturing workers out of work. Although 3D printing will not eliminate the sector completely, it will definitely reshape the job requirements in the industry. Fewer laborers will be required and those that are will need to be skilled at their job, and have an understanding of technology and the different components.
In addition to the revolutionized workplace and job, a design comes the concern of accuracy, another ethical issue of the information age mentioned by Richard Mason. The accuracy and dependence of the 3D printer may be ethically concerning. For instance, if the 3D printer is printing an implantable medical device and the resolution becomes defective or it simply doesn’t print correctly it may cause extreme harm to the patient. If we become dependent on the accuracy of such technology it may be a concern and should ultimately be regulated effectively.
Impact on Medicine
3D printing is becoming heavily implemented in medicine ranging from printing a medical device, prosthetic, to implants. Another name 3D printing in medicine has obtained is bioprinting. Multiple ethical issues such as access, safety, and enhancement have quickly arisen as bioprinting has become more frequently implemented in hospitals.
Access, a third ethical issue mentioned by Richard Mason, is a large concern for 3D printing in medicine. It becomes a concern because essentially you are creating a personalized medicine where more money will allow quicker access to a 3D printed part for specialized treatment. This ultimately increases the health disparities between rich and poor. However, we must also recognize that there is an increase in access for some devices such as prosthetics specifically in the case of a child in need of prosthetic when they are continually growing out of the fit.
Another ethical issue bioprinting creates is safety concerns. As mentioned above the accuracy of specific implants are integral to their success. If a defective part is placed into a patient severe consequences may occur. In addition, researchers are continually working to develop 3D printed organs specific to the patient. It becomes a concern when testing of these developed organs will even be safe to actually implement in a clinical trial. The potential development of a "black market" or the distribution of organs printed in a less than ideal environment to less than sufficient standards for cheaper costs are also a potential concern for the future of bioprinting technology.
An issue with using 3D printing involves the topic of human enhancement. While the technology can be used to develop replacements for organs and bones, it is hypothesized that it could also be used to develop features that can enhance humans to go beyond normal capabilities. For instance, is it ethical to replace existing bones with artificial ones that are stronger and more flexible? Should people consider implanting new lungs that oxygenate blood more efficiently? A similar comparison would be the use of performance-enhancing drugs in the sports field. Such use is considered cheating, unbalancing the level playing field. An area where 3D bioprinting seems useful would be for military personnel with the idea of enhancing soldiers to be less susceptible to being wounded in battle. Such capabilities in 3D technology may lead to a new kind of arms race and deeper ethical and social issues. On the other hand, 3D printing can duplicate the scare resources of the human body that people would otherwise have to wait for and could risk dying while they are on a wait-list. While 3D printed human parts can be printed as stronger and thus better, it will be a long time before our printing technology can reach this level.
4D printing incorporates an additional dimension: the function of time. The team dubbed "Self-Assembly Lab" at Massachusetts Institute of Technology collaborated with Stratasys, a major 3D printing manufacturer, and the software corporation Autodesk Inc to develop a custom-built and adaptable technology.
As an extension of 3D printing, 4D printing aims to skip the step of assembling the printed material ourselves to having them self-assemble as well as autonomously reshape over time. These programmable materials are created with multi-material 3D printing and their responses to changes in the environment (mimicked with simple energy inputs of water, heat, and light), as well as geometric code .
Skylar Tibbits, a co-director and founder of Self-Assembly Labs, gave a demonstration of 4D printing at a TED Talk in 2013 , showing how a single 1D strand dipped in water could proceed to self-fold into the letters 'M I T'.
This complex technology introduces many possibilities in engineering. It has already appeared in several businesses, such as sportswear, but soon, the focus may shift from the inorganic world to organic life. Following the same concerns that arise from 3D printing, there is also the opportunity for misuse of the programmable matter, and issues in regulation concerning intellectual property law and patenting.
- Matias, Elizabeth, and Bharat Rao. "3D Printing: On Its Historical Evolution and the Implications for Business." 2015 Portland International Conference on Management of Engineering and Technology (PICMET) (2015): n. pag. Web. <http://faculty.poly.edu/~brao/3dppicmet.pdf>
- Kumar, Upender, Manoj Pandey, and Tejender Singh Rawat. "Review on 3D Printing Technology and Possible Technological Improvements" <http://www.academicscience.co.in/admin/resources/project/paper/f201505111431317592.docx>
- Hoffman, Tony. "3D Printing: What You Need to Know." PCMAG. PCMAG.COM, 04 Jan. 2016. Web. 21 Mar. 2017. <http://www.pcmag.com/article2/0,2817,2394720,00.asp>
- "History of 3D Printing." 3D Printing Industry. 3D Printing Industry, n.d. Web. 21 Mar. 2017. <https://3dprintingindustry.com/3d-printing-basics-free-beginners-guide/history/>
- 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.237–241, April 1981
- "RepRapGPLLicence." RepRapGPLLicence. RepRapWiki, n.d. Web. 21 Mar. 2017. <http://reprap.org/wiki/RepRapGPLLicence>
- "How Dutch Team Is 3D-printing a Full-sized House." BBC News. BBC, 3 May 2014. Web. 21 Mar. 2017. <http://www.bbc.com/news/technology-27221199>
- "What We Do." Not Impossible. Not Impossible, LLC, n.d. Web. 21 Mar. 2017. <http://www.notimpossible.com/whatwedo>
- D'Aveni, Richard (March 2013). "3-D Printing Will Change the World". Harvard Business Review. <https://hbr.org/2013/03/3-d-printing-will-change-the-world>
- "Gcode" wikipedia.org. April 2018 en.wikipedia.org
- Simplify3D Print Quality Improvement Guide, April 2018 [simplify3d.com/support]
- Cura slicer home website [ultimaker.com]
- Slic3r home website [slic3r.org]
- Simplify3D home website [simplify3d.com]
- Bernhard Mueller, (2012) "Additive Manufacturing Technologies – Rapid Prototyping to Direct Digital Manufacturing", Assembly Automation, Vol. 32 Issue: 2, https://doi.org/10.1108/aa.2012.03332baa.010
- "Benefits & Commercial Value." 3D Printing Industry. 3D Printing Industry, n.d. Web. 21 Mar. 2017. <https://3dprintingindustry.com/3d-printing-basics-free-beginners-guide/benefits-commercial-value/>
- Could 3D printing solve the organ transplant shortage? 
- Liver success holds the promise of 3D organ printing. 
- Mason, Richard O. "Four Ethical Issues of the Information Age." Four Ethical Issues of the Information Age). N.p., 21 Aug. 2012.
- "Gartner Reveals Top Predictions for IT Organizations and Users for 2014 and Beyond." Gartner. N.p., n.d.
- "3D Printing Raises Ethical Issues in Medicine." ABC - Australian Broadcasting Corporation. N.p., 10 Feb. 2015.
- "Self-Assembly Lab." Self-Assembly Lab. Massachusetts Institute of Technology, n.d. Web. 21 Mar. 2017. <http://www.selfassemblylab.net/>
- "Self-Assembly Lab 4D Printing." Self-Assembly Lab. Massachusetts Institute of Technology, n.d. Web. 21 Mar. 2017. <http://www.selfassemblylab.net/4DPrinting.php>
- Rieland, Randy. "Forget the 3D Printer: 4D Printing Could Change Everything." Smithsonian.com. Smithsonian Institution, 16 May 2014. Web. 21 Mar. 2017. <http://www.smithsonianmag.com/innovation/Objects-That-Change-Shape-On-Their-Own-180951449/>
- Tibbits, Skylar. "The Emergence of "4D Printing"." Skylar Tibbits: The Emergence of "4D Printing" | TED Talk | TED.com. TED, Feb. 2013. Web. 21 Mar. 2017. <https://www.ted.com/talks/skylar_tibbits_the_emergence_of_4d_printing>
- Campbell, Thomas A., Skylar Tibbits, and Banning Garrett. "The Next Wave: 4D Printing." AccessScience (2014): n. pag. Web. <http://www.atlanticcouncil.org/images/publications/The_Next_Wave_4D_Printing_Programming_the_Material_World.pdf>