You don't bring a 3D printer to a gun fight -- yet

Consumer-level 3D printing could change guns and gun control as we know them. So how soon are we likely to see 3D-printed plastic firearms? And what are the legal issues? CNET's Rich Brown sights in on the DIY gun movement.

Rich Brown Former Senior Editorial Director - Home and Wellness
Rich was the editorial lead for CNET's Home and Wellness sections, based in Louisville, Kentucky. Before moving to Louisville in 2013, Rich ran CNET's desktop computer review section for 10 years in New York City. He has worked as a tech journalist since 1994, covering everything from 3D printing to Z-Wave smart locks.
Expertise Smart home | Windows PCs | Cooking (sometimes) | Woodworking tools (getting there...)
Rich Brown
12 min read
Perhaps the best known plastic gun, from 1993's "In the Line of Fire."
Perhaps the best-known plastic gun, from 1993's "In the Line of Fire." Internet Movie Firearms Database

Welcome to the dark side of 3D printing.

The hobby is best known for creating colorful toys and trinkets, but some enthusiasts are working on design files that would allow anyone to print a working gun. These don't exist yet, but some believe it's only a matter of time.

Why would a 3D-printed gun be appealing? For one, it could potentially be cheap. You can buy a preassembled 3D printer for about $500. A spool of ABS plastic to print with goes for $50. Depending on where you shop, you can buy .38 Special ammunition for 30 cents a round. The plans will undoubted be distributed free like so many MP3s.

In fact, plans for working gun parts already exist. They can be found on a site called Thingiverse and on similar sites, alongside thousands of free plans for toys, jewelry, tools, and design equipment.

Thingiverse is a creation of Brooklyn, N.Y.-based MakerBot and its CEO, Bre Pettis. Pettis and his company have become the de facto faces of 3D printing thanks to regular appearances in mainstream and tech media talking about how 3D printers democratize manufacturing. Pettis usually demonstrates this idea with brightly colored remote-control cars, robots, and other toys made with MakerBot printers. MakerBot and Pettis don't really talk about files related to gun parts.

The more familiar side of 3D printing.
The more familiar side of 3D printing. CNET

That doesn't mean the issue has gone unnoticed, with the intersection of 3D printing and firearms having made the news a few times this year. In June, Michael "HaveBlue" Guslick reported on his blog about successfully test-firing a homemade gun whose key component, the lower receiver, he made from ABS plastic on a '90s-era Stratasys FDM 1600 3D printer.

And in August, Forbes' Andy Greenberg wrote about a group called Defense Distributed, which has some lofty goals as mapped out in the video below. In practical terms, their immediate aim is to create a design file for what they call a Wiki Weapon, a functional, 3D-printed firearm.

The increased attention on printable guns comes as Defense Distributed is approaching a firing test, said Cody Wilson, a University of Texas graduate student and the chief spokesman for the group. Depending on the outcome of that testing, 3D-printing companies, file-hosting sites, and law enforcement and legislative groups may have to tackle a challenging set of questions regarding the manufacture and regulation of firearms, both in this country and abroad.

All of this might sound exciting, alarming, or nonsensical, depending on your personal beliefs and familiarity with guns and gunsmithing. Setting aside any moral leanings, the fact is that the idea will need to overcome significant material and legislative hurdles before you can crank out a working, legal, 3D-printed gun in the United States. On the physical side, the ABS printing plastic might not be strong enough to make a stable enough weapon. And law-abiding, gunsmithing Americans must first face numerous federal, state, and local gun regulations and bureaucratic procedures that may not take kindly to people printing their own firearms.

None of that means printing a gun is impossible.

Darwin Award, or upending the means of production?
On his blog, Haveblue.org, Guslick offers thorough documentation of the process he followed to design, print, fine-tune, and test his 3D-printed receiver. Guslick also addresses the reception to his project by the greater 3D-printing community, as well as the ensuing media swirl and the feasibility of the Defense Distributed project. All of those topics are worth reading about, but that last part will be of particular interest to would-be gunmakers.

Michael Guslick's homemade pistol, with a plastic, 3D-printed lower receiver designed for an AR 15 hunting rifle.
Michael Guslick's homemade pistol, with a plastic, 3D-printed lower receiver designed for an AR 15 hunting rifle. Michael Guslick

You can make a receiver like Guslick's out of plastic because it houses only the basic mechanical parts of a firearm -- the trigger mechanism, the magazine, and other components. It's the barrel of a gun and/or the firing chamber, both of which you attach to the receiver, that must be strong enough to contain the heat and explosive pressure that comes from firing a round. A project like that of Defense Distributed and its Wiki Weapon poses a much harder challenge, as Guslick explains on his site (links added where appropriate):

The problem is that even the strongest 3D-printable thermoplastic currently available for the FDM process (Ultem 9085) doesn't even have half the tensile strength needed to withstand the 24,000 psi maximum allowed chamber pressure of the .22LR round as defined by SAAMI (the Sporting Arms and Manufacturer's Institute).

As such, yes, a 100 percent 3D-printed gun made on a RepRap could certainly go "bang," but even with a barrel of large enough diameter to keep it from exploding, there would be so much deformation in the bore that most of the available energy would be sapped by gas leakage around the projectile (to say nothing of the utter lack of accuracy). In the end, you'd have a smoking, charred crater left for a barrel bore after the single shot.

Wilson at the University of Texas says he intends to find out just what's possible with ABS plastic. "I'm excited about the question, because I'm interested to see how it fails," he told CNET.

That doesn't mean Wilson expects to fail. He referred me to this list of barrel pressure tolerances, and said Defense Distributed plans to test .38 Special ammunition, as well as .45 Long Colt, both of which have lower maximum pressure output than the .22. And according to Wilson, "operational pressure is also about half of the SAAMI-suggested maximum tolerances."

Bringing in a specialist
Ryder Washburn is the vice president of Specialists Ltd., the East Coast's largest provider of prop weaponry for film, TV, and theater. "What we try to do is the opposite of what you're talking about," Washburn said. "We want to take as much 'gun' out of our products as possible. Essentially we want to stay 10 feet back from the edge of making an actual firearm. But in order to do that, you have to know where the edge is."

A homemade pistol made from common hardware.
A homemade pistol made from common hardware. Wikipedia

I asked Washburn about Wilson's likelihood of success. "Using lower-pressure ammunition sounds like a good decision, but it depends on how you define success. If his goal is to fire a bullet and not blow his hand off, I give him a 50 percent chance."

To my disappointment, I did not get to meet Washburn at his SOHO office in New York ("It's pretty hectic here," he told me). Instead, we met at a nearby coffee shop.

"People get excited by additive manufacturing [like 3D printing] because it seems like you're making something out of thin air. But it has been possible to make guns with reductive technology, like a CNC mill, for years, and it works the same way as a 3D printer. Most of the work goes on in 3D-modeling software. Then you take the design file from the computer and send it to the machine to build. You can make a working metal gun with a $3,000 CNC machine. If all you want to do is make a cheap gun, you can go down to Home Depot and build one with $20 worth of parts."

Washburn also backed up Guslick's assessment that using Ultem or any other plastic-based FDM printer feedstock to make a complete, functional firearm would be very difficult, if not impossible. I asked him if it was possible for a gun made entirely from ABS plastic to fire a .22 caliber round, the same ammunition Defense Distributed had in mind initially. "You might be able to do that, but it would take a lot of design work, and a lot of research and funding. And the end result would still be an inferior product compared with what you can currently make using traditional machine tools."

I was not invited down to the Specialists Ltd. shop.
I was not invited down to the Specialists Ltd. shop.

For Wilson, making a practical, working gun isn't necessarily the point. "We have to start here. This is the fundament. It's the beginning." The Defense Distributed project is less about the gun, according to Wilson, than about democratizing manufacturing technology. His intention is that "the non-expert user will have the ability to make a gun with just a click."

As Washburn points out, you can already do that with a CNC milling machine. But, Wilson adds, it still requires some expertise in the assembly. Wilson also argues that 3D printers are unique in their potential to print using multiple materials. That, he says, gives 3D printing a more capable future than traditional machine tools.

In summing up my goal for this article to Wilson, I said that it was in part to communicate the present-day reality of using a 3D printer to make a plastic gun and submitted that it was not currently feasible. Citing his team's upcoming ammunition test, he disagreed. "Literally, it might be possible to print out a gun in a few weeks."

Not everyone will agree with Wilson's goals or philosophy, but enough people do that the project has made substantial progress toward its $20,000 fundraising goal. After stagnating at just over $1,000 toward the end of last week, on the evening of August 30, the group received a $10,000 windfall. Wilson tells me they also have a commitment for matching funds for every dollar above $10,000. According to the Defense Distributed Web site, the fundraising tally currently stands at $11,304, and he intends to conduct his firing test soon.

The law won
But is any of this even legal? From the 1934 National Firearms Act to the 1968 Gun Control Act (PDF) and a variety of other laws, the federal government has all kinds of regulations pertaining to firearm manufacturing and possession. And those laws supply only the minimum standard. Layer state and local laws on top of those, and the legal obligations for the would-be home gunsmiths become rather burdensome.

Expect to spend a lot of time here if you plan to make a 3D printed gun.
Expect to spend a lot of time here if you plan to make a 3D printed gun. Rich Brown/CNET

From a federal point of view, you have three primary legal considerations before you hit print.

If you aim to sell your services as a gunsmith (e.g., "I charge $50 an hour to make a gun") or you intend to sell the weapon once you've made it (e.g., "I charge $500 for this particular gun"), you need to obtain a federal manufacturer's license. If the weapon is for personal use, no manufacturing license is required.

You then need to consider the kind of weapon you intend to make. Crafting a Title I class weapon at home -- a long-barreled semi-automatic or single-action rifle, a long-barreled shotgun, or a traditional pistol or a revolver as defined by the Gun Control Act -- generally requires no preliminary paperwork. You may still need to register the weapon once you've made it (depending on state and local laws), but, federally speaking, you're free to engage in the act of making it without any prior permission. The problem is that using a consumer-grade 3D printer to make a functional firearm that meets the specifications of a Title I weapon would be extremely difficult, not to mention impractical, for the reasons outlined above.

Instead, any successful design would most likely be considered a Title II-class weapon as defined by the National Firearms Act, specifically one that fits the "Any Other Weapon" category.

Get ready for some paperwork
Title II-class weapons are the more heavily regulated firearms under federal law. Guns in this category consist of, among other things, machine guns, sawed-off shotguns, explosive devices, and what the U.S. government calls "Any Other Weapon." The latter includes pen, cane, and other gadget-type guns, and smooth-bore pistols. According to David Goldman, managing partner of Jacksonville, FL's Apple Law Firm, and publisher of the NFA Gun Trust Lawyer blog, the Bureau of Alcohol, Tobacco, and Firearms would most likely put a 3D-printed plastic gun in that category.

ATF F 5320.1, aka the Application to Make and Register a Firearm.
ATF F 5320.1, aka the Application to Make and Register a Firearm. Rich Brown/CNET

Assuming your design does fall under the Title II Any Other Weapon classification, federal law mandates that before you make it, you fill out ATF Form 5320.1 (PDF), aka Form 1, aka the Application to Make and Register a Firearm. You then need to submit it and have it approved by the ATF.

As part of the approval process, an ATF spokesperson informed me that the agency will want to see the design for your homemade gun. This will help them determine its classification, as well as whether the weapon would be legal for you to possess in your state or municipality.

Form 1 also requires that you receive approval from a local law enforcement officer. Others have sued after failing to secure this approval for the transfer of weapons between owners, which requires a different form, but Goldman is familiar with no case law supporting those who have been unable to obtain this approval for a Form 1 application.

You must also consider the obscure but very relevant Undetectable Firearms Act. It was Wilson who told me about this law ("I'm doing your research for you," he joked).

The Undetectable Firearms Act says, simply, that you may not manufacture or possess a firearm that cannot be detected by an airport metal detector. The law is a product of the debut of the Glock 17 handgun that caused a stir in the 1980s for its composite plastic components. That gun was itself never capable of defeating an airport metal detector, but the law is still in place regardless, although it's due to expire in December of 2013.

Trying this at home
There are more legal considerations to making a Title II-class gun, but also interesting is the case of the Guslick's receiver design. According to federal law, the receiver is so integral to the specific functionality of a given weapon that the receiver itself is considered a firearm. Guslick's design in particular mirrors that of a Colt AR 15 hunting rifle, making it a Title I-class weapon. In New York City, possessing Guslick's receiver would be illegal.

My smaller scale print of Michael "HaveBlue" Guslick's AR 15 lower receiver design.
My smaller-scale print of Michael "HaveBlue" Guslick's AR 15 lower receiver design. Sarah Tew/CNET

It's for that reason that I printed a significantly reduced-scale version of Guslick's receiver from ABS plastic on a MakerBot Replicator 3D printer. It's also why I felt even more secure when the print came out a little mangled after one corner pulled up from the build surface during printing. It's also the reason why, even despite the small size and the imperfect print, I destroyed the mini receiver last week.

I printed the receiver first to see if the end result seemed like a feasible gun part. I'm neither a materials scientist nor a gunsmith, nor am I even a particularly adept 3D-printer user, but my miniature receiver felt solid enough, at least to me, to accept some mechanical internal components and mounting hardware.

"This is about 25 percent scale," Washburn said of my mini receiver. "There's probably nothing illegal about this. If you made it at 100 percent scale, I wouldn't want to be your lawyer."

The remains of my miniature AR 15 receiver.
The remains of my miniature AR 15 receiver. Sarah Tew/CNET

Even if a consumer-level 3D printer can't currently make a functioning gun, it can make some rather serious gun components. "I'd hate to see some 15-year-old get in trouble for printing this full-sized," Washburn said.

I am become death, the destroyer of my garage
The obvious retort to any discussion of the legalities of making your own firearms or firearm components, 3D-printed or otherwise, is that criminals don't care about gun control laws. And even if it's impractical, if not downright impossible, to make your own plastic gun now, as 3D-printing technology improves and grows you might envision a near-term future where crooks regularly arm themselves with cheap, easily reproduced plastic firearms.

Even if you dial down the scare rhetoric, 3D printing at the very least seems like it could disrupt the idea that a government can regulate guns or their manufacture. Defense Distributed outright claims that kind of disruption among its goals.

"In a sense, every dollar [that you donate to their project] is a statement to these international kleptocrats that this isn't in [their] control anymore."

Here's the problem with that idea. As Washburn pointed out, you can already make a cheap gun with a trip down to the hardware store. And with only a little training, you can already use relatively affordable, widely available machine tools to mass-produce functioning weapons.

Defense Distributed is closing in on its $20,000 fund-raising goal.
Defense Distributed is closing in on its $20,000 fund-raising goal. Rich Brown/CNET

This is not to say that zip guns and other illegal homemade weapons don't currently exist. Yet despite the widely distributed means of production and low financial and knowledge requirements, the regulation-shaking, homemade gun-making revolution hasn't happened in this country.

Washburn, the ATF, and gun rights attorney Stephan Halbrook all believe current U.S. legislation is already well-equipped to handle the prospect of a plastic, 3D-printed firearm. You never know, of course. "You might find a legislator somewhere who wants to do something about it," Halbrook said. But the federal government has been regulating alternative gun designs, the Any Other Weapon, since the National Firearms Act of 1934. Wilson counters that if his group can design an effective, easily distributed plan for a printable plastic gun, "there is just not enough manpower to control it."

"3D printing 20 years from now is a different animal," Washburn said, allowing at least the possibility that printing a functional firearm might one day become more practical. Even if it does, it will only offer another means to an end that we can already accomplish easily. "This has all been done before," Washburn said, "and there are smarter ways to do it."

Meanwhile, Defense Distributed is going forward with its testing.