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.

Other than the materials that can be used, what limitations do lower-end 3-D printers have at this time?

Another limitation is accuracy. These machines don’t have the temperature control of higher-end systems, and consequently the dimensional accuracies suffer. The more expensive industrial systems take into account how much a part will change as it goes through the process of being made. Better temperature control enables a printer to better adjust for changes in the material as it is layered, solidifies and shrinks. If you don’t take those changes into account, some layers might be farther apart, creating voids that prevent the finished product from being as strong as it could be.

All of these things can be overcome. There are lots of people working in their homes on inexpensive desktop systems [like those MakerBot produces] who are going to be geeky, experimenting and optimizing their systems. They’ll write their own code and figure out how to compensate for their equipment and materials. That’s what my students do. There is some knowledge that you have to develop to use these systems optimally.

As inventors develop this knowledge, are there concerns that more of them will experiment with 3-D printed weapons?

3-D printing is not the only enabling technology here. 3-D printers may be a little less complicated to use than [some computer numerical control (CNC) systems that manufacturers use to make tools], but you still can buy a CNC machine today and use that to build weapons. In fact, I would be much more scared of people who have expertise in machine shops [making weapons] than I would of someone using a 3-D printer.

And, even if you don’t print the parts for the weapons yourself, there’s an entire industry that makes parts on demand today using 3-D printing. You can upload your file online without even speaking with anyone and pay for it with your credit card.

How soon will higher-end 3-D printers capable of using better materials become affordable for hobbyists and inventors?

I don’t know how much the cost can come down for some high-end systems because they are big machines and they use more expensive industrial components, which limits how much the price can be reduced. And the price of high-end systems may not be the limiting factor for hobbyists because they can take a desktop system [like those made by MakerBot] and supercharge it, and there’s no technical reason you couldn’t use it to print a weapon.

How would you supercharge a desktop 3-D printer to give it that capability?

I may enclose it so that I can reach higher temperatures and work with [stronger, more durable] materials. I might also do this by modifying the printer’s heater to make the printhead hotter.

People are less likely to modify an industrial system because companies like Stratasys don’t give you access to their printer’s source code. MakerBot and other desktop printer–makers do. That means I can write my own code to change things on these lower-end systems but I can’t [change] that on a Stratasys system. Even the materials used by industrial systems are controlled. A canister of material used in a Stratasys printer even has a microchip that knows what and how much material it contains.

What impact will Wilson’s experiment have on 3-D printing?

It concerns me a little, but I think this type of project was inevitable. We would all like these technologies to be used for the benefit of society, and I believe these benefits far outweigh the risks. There are lots of wonderful examples—customized hearing aids, 3-D printed electronics and even shoes as well as [efforts to print artificial human] organs. The government will ultimately decide whether the technology should be regulated, but I see these technologies completely disrupting the way we make products, and bringing innovative, entrepreneurial manufacturing work back to the U.S. We’ve traveled too far down the road to turn back at this point. With these technologies, the future is limited only by one’s imagination.

A robot that can reproduce the dexterity of the human hand remains a dream of the bioengineering profession. One new approach to achieving this goal avoids trying to replicate the intricacy of the bones, joints and ligaments that produce our most basic gestures.

A Sandia National Laboratories research team has adopted just such a strategy by designing a modular, plastic proto-hand whose electronics system is largely made from parts found in cell phones. The Sandia Hand can still perform with a high level of finesse for a robot, and is even capable of replacing the batteries in a small flashlight. It is expected to cost about $10,000, a fraction of the $250,000 price tag for a state-of-the-art robot hand today.

The researchers were able to scrimp in a number of clever ways. “One was scouring the globe for the least expensive, highest-performing components like motors, gears, etcetera,” says Curt Salisbury, the project’s principal investigator. “Another was to build the entire electronics system from commodity parts, especially those found in cell phones. We also moved from metal structural elements to plastic, being careful to design the structures so plastic would provide adequate strength.”

The Sandia Hand’s fingers are modular and affixed to the hand frame via magnets. This gives the researchers the flexibility to design interchangeable appendages tipped with screwdrivers, flashlights, cameras and other tools. The fingers are also designed to detach automatically to avoid damage if the hand hits a wall or other solid object too hard. The researchers say the hand can even be manipulated to retrieve and reattach a fallen finger.

The Hand’s current incarnation has only four fingers, including the equivalent of an opposable thumb. “It turns out that for a wide range of manipulation tasks that humans do, four fingers is enough,” Salisbury says. Still, future iterations of the Hand could have any number of fingers and any arrangement of those fingers without adding much cost or complexity, he adds.

Although the Hand might someday be programmed to operate autonomously, for now a human controls the device using either a sensor-laden glove or a basic control panel. The glove is a custom design that reads a person’s hand posture and attempts to replicate that with the robot hand, Salisbury says. The communication protocol right now is a USB cable, but could be upgraded to include any wireless communications approach, he adds. The team’s goal is to develop a glove that costs about $1,000.

At such a low cost, and with the Defense Advanced Research Projects Agency (DARPA) funding the project, the Hand might be a welcome addition to mobile robots involved in disarming and disposing of improvised explosive devices (IEDs). The U.S. military has deployed thousands of unmanned ground robots worth hundreds of millions of dollars to disarm IEDs used against troops in Afghanistan and Iraq over the past decade. Many of these devices, such as iRobot’s PackBot, are driven by remote control into dangerous areas where they use clamp-like metal claws to search for and dispose of bombs. A significant amount of the money spent on these battle bots goes toward spare parts to replace those damaged in the field. One of Sandia’s goals is to offer greater proficiency at disarming (rather than detonating) bombs.

Sandia researchers are experimenting with upgrades to the Hand, including a palm with two embedded cameras that convey stereo images to a human operator during a grasping sequence. “After that,” Salisbury says, “we hope this technology will move to field tests.”

In the video below, the Sandia Hand demonstrates a number of capabilities, including lifting a suitcase, picking up a telephone handset and, perhaps most impressively, dropping a AA battery into a flashlight.

Images and video courtesy of SandiaLabs.

About the Author: Larry is the associate editor of technology for Scientific American, covering a variety of tech-related topics, including biotech, computers, military tech, nanotech and robots. Follow on Twitter @lggreenemeier.
The views expressed are those of the author and are not necessarily those of Scientific American.