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A University of Texas at Austin law student has demonstrated to the world that any ambitious tinkerer can make a handgun almost entirely out of 3-D printed parts. Cody Wilson’s revelation is not likely to lead to an arsenal of plastic zip guns anytime soon, but it does raise a number of hairy questions about a technology that, until now, has been highly touted as central to the future of manufacturing in the U.S.
Images and video of Wilson posing with and firing his “Liberator” handgun have made the rounds on the Internet in recent days. It’s a stark contrast to the image that 3-D printing, or “additive manufacturing,” proponents have pursued thus far, where the world benefits from robotic prosthetics, replacement hips and other biomedical wonders manufactured layer by layer out of molten plastic or metal, as dictated by a CAD (computer-aided design) file.
Wilson’s gun consists of 15 parts assembled after being printed individually in a Stratasys Dimension SST machine out of white ABS plastic—a polymer made from the chemical compounds acrylonitrile, butadiene and styrene. Only the gun’s firing pin (a common nail) and an obligatory piece of steel embedded in the handle—so that it does not violate the Undetectable Firearms Act (pdf)—are metal. Wilson has made the design files needed to create the Liberator—that fires standard handgun rounds—available as a free download for anyone interested in replicating his work.
Wilson positions himself as a protector of civil liberties—in particular “popular access to arms”—and has founded a nonprofit called Defense Distributed to further this goal. His libertarian views are not unlike those of free, open-source software advocates or hackers who take down Web sites and pick apart popular software like Windows to prove they are not as secure as they appear—except for the small detail that he wants to empower people to make devices that can harm or kill other people. (He’s also published blueprints for 3-D printing part of an AR-15 semiautomatic rifle.)
Technically speaking, Wilson’s so-called “Wiki Weapon” pushes the boundaries of 3-D printing capabilities, especially those of lower-end systems not able to work with anything stronger or more durable than ABS plastic. Although the Liberator currently fires only a single shot, better materials as well as improved designs and post-processing techniques might ultimately lead to a weapon that can shoot multiple rounds without breaking down.
To learn more about the potential impact of Wilson’s work on the world of 3-D printing, Scientific American spoke with Ryan Wicker, director of the University of Texas at El Paso’s W. M. Keck Center for 3-D Innovation. Wicker shared his thoughts about Wilson’s invention, the technical challenges of making a 3-D printed gun and the reality that the unbridled creativity promoted by 3-D printing was destined to take a darker turn.
[An edited transcript of the interview follows.]
What was your reaction when you learned that someone had printed nearly all of the components needed to assemble a handgun using a 3-D printer?
This story has been developing for months, if not years, so it was pretty anticlimactic. I probably first became aware of what [Wilson] has been doing when Stratasys went in and confiscated the printer they leased to him [in October. I have been hearing for years about people using 3-D printers to make parts for guns. In the evolution of 3-D printing it’s certainly natural for things like this to happen.
Are there specific challenges to making a working firearm using 3-D printed parts?
Building the parts with a high level of dimensional accuracy would be one challenge and the material performance would be another. A firearm experiences a high-energy impulse in the chamber, where the gun components start off at ambient conditions but are subjected very quickly to higher temperatures and pressures. This sudden change can compromise the structural integrity of the gun, even possibly making it explode.
What is the significance of Wilson making most of his gun parts out of ABS plastic?
ABS is an inexpensive polymer typically used by the type of 3-D printer that he used. There are plastics that are stronger, more durable and perform much better than ABS, but those higher-end materials require higher-end machines than what he had.
Why is ABS the standard plastic for lower-end systems?
ABS is just a commodity, a commonly used plastic that the automotive industry has used for years to create injection-molded parts. Different 3-D printing systems work differently, but [Wilson’s] uses an extrusion-based process that’s analogous to a hot-glue gun. ABS’s extrusion temperature [the point at which the polymer starts to deform and can be squeezed out into layers] is lower than other, more capable plastics. It doesn’t require a more expensive system that can [operate at] higher temperatures.
Why not use a more durable plastic?
Stratasys offers a more expensive plastic called Ultem, which potentially would be a better performer than ABS for this application. But you can’t print this type of high-end material using the low-end [$20,000] industrial printer that [Wilson] used. You need a high-end machine that costs anywhere between $100,000 and $400,000 to be able to use those better plastics. Although it’s not possible now, that doesn’t mean someone couldn’t develop the capability to work with better plastics on low-end systems.