3D printing guns at home: Does new technology change America's gun control debate?

One celebrity calls 3D-printed guns "downloadable death." But how practical is 3D-printing technology for the creation of guns? Where does 3D printing fit into today's gun debate?

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Alyssa Milano, yesterday in CNN, described 3D-printed guns as "downloadable death." In Pennsylvania, rushed hearings blocked a Texas-based company from offering downloadable gun plans in that state. Expect more and more reports on 3D-printable guns in coming days, as 3D-printable object files for guns become available online.

Gun control is a deeply charged topic in the US. According to the non-profit Gun Violence Archive, there were 33,609 gun incidents in America from January to July 2018. There were 8,426 deaths and 199 mass shootings. Clearly, we have a horrifying problem.

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But will the existence of downloadable 3D models for 3D-printable guns make that problem worse? Where does the idea of 3D-printed weapons fit in the overall debate about guns in America? Let's approach the problem from a purely technical perspective and see if that offers any insights.

Guns are ranged weapons: They can inflict damage outside of the reach of their users. Guns can also sustain rate of fire. (Rate of fire is the time between one bullet leaving the chamber and the next.) In a battle, the squad with a better rate of fire will usually win.

So, the first question we have to ask when talking analytically about 3D-printed guns is: Can they function as ranged weapons and can they sustain rate of fire? Can the plastic hold up to the pressures involved in the explosive force that sends a bullet flying?

There is certainly proof of concept. In 2013, we wrote about the Lulz Liberator, a 3D-printed gun that could fire up to eight shots. This engineer used the same model printer I have sitting in my garage and have reviewed here: A Lulzbot printer.

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So, yes, you can 3D-print a weapon capable of firing a bullet. But can you print, using a fused deposition modeling (FDM) printer, an entire AR-15 semi-automatic weapon? No. The way an FDM printer works is by extruding layers of plastic one on top of the other, until a certain depth is built up.

While the idea of fabricating guns out of spools of plastic is certainly headline-making, it's an over-simplification of the question of home fabrication of weapons of all kinds.

For most applications, FDM printing is pretty amazing. But when it comes to strength, FDM tends to break down on the layer lines. In other words, it can crack. Work has been done by filament vendors (the folks making the material that 3D printers print) to make stronger materials, ranging from metal-infused to carbon-fiber-infused plastics, and even nylon (which is both strong and somewhat flexible).

Additionally, the Lulz Liberator was printed in ABS plastic. ABS is extremely difficult to print in because it cools at an inconsistent rate. As a result, you often get puckering or distortion of prints. Printing a perfect gun barrel in ABS plastic is doable, but requires more craftsmanship and skill than merely downloading an STL file and sending it to your printer.

While the idea of fabricating guns out of spools of plastic is certainly headline-making, it's an over-simplification of the question of home fabrication of weapons of all kinds. That's because 3D printing is not the only desktop fabrication technology available to makers today.

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3D printing is additive, in that layers of material are added to each other stroke by stroke. But laser cutters and CNC machines are subtractive. These machines allow makers to remove material programmatically, which allows for operations like fabricating aluminum and even light steel parts. Again, like the 3D printing technology available today, other desktop fabrication tools require a level of skill to create the result.

The argument those against 3D-printed guns often bring out is that once plans are available online, anyone can make untraceable guns. Let's think about that.

A neighbor of mine has a large collection of sewing patterns and a couple of sewing machines. Last year, I watched her take a ball gown pattern (a rather complex engineering diagram on its own) and, using material purchased from the store, create an exquisite gown.

You could give me the same pattern and the same machines she has, and I'd produce a bundle of cloth that was a big mess. That's because I don't have her skill as a sewist.

Today, the mere availability of a 3D printer and a gun plan is not enough to produce a weapon. Fabrication skill on the part of the weapon maker is a pre-requisite. Whether that will always be the case is a matter of constant discussion among 3D-printing enthusiasts, because the holy grail for many 3D makers is the ability for anyone to download a file from the internet and transform that file into a finished object.

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We are years away from that capability. But that doesn't mean forward-thinking legislators, activists, and law enforcement personnel shouldn't be thinking through this issue.

The skill required for fabrication is important in this discussion. Skilled craftsman can make guns using a variety of metalworking power tools available from the likes of Harbor Freight or Amazon. Other tools, like 3-axis milling machines, can be used to create devastating weapons. But because traditional metalworking tools (universally available and taught in most high schools) aren't sexy, they're not the focus of TV stars and breathless news reports.

I don't see TV stars calling 3-axis milling machines "downloadable death," although they can be used to create devastating weapons as well.

Today, making a functional 3D-printed AR-15 is not just a matter of a download. First, there need to be metal parts, either purchased as components or fabricated. There's no way an FDM printer can lay down plastic that's strong enough to handle the forces inside a semi-automatic weapon like an AR-15.

But a 3D printer could certainly be used to make non-shock impact components, like the grip, which does reduce the sourcing challenge for anyone wanting to create such a dangerous weapon.

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Will we see consumer-level 3D printers capable of printing in stronger filaments, and capable of fusing metal components to plastic ones? Probably. Will those printers be capable of creating components capable of withstanding explosive shock? Not right away.

This is a deeply nuanced problem and unyielding, dogmatic bloviating from either side won't help solve it.

There is another technical issue here. Because plastic can fracture, the danger of a 3D-printed gun may well be less about using the gun as a weapon to attack others, but instead about whether or not ill-informed makers will attempt to fire such a creation, and have the thing explode in their hands.

Milano does make a valid argument, though. She says, "Imagine the damage one of these guns, even if it was only capable of firing one shot, could do aboard a plane. Or in a government office. Or in your child's classroom."

And that does take us to a very important second issue in our discussion: regulation. 3D-printed guns can be created by someone with a level of skill. They can be untraceable, and if enough of the componentry is plastic, they could be undetectable by metal detectors. In other words, 3D-printed plastic weapons, however limited in function, could be used by terrorists.

Gun control is a difficult problem for our society. It's not about 3D-printed weapons vs. conventional weapons. It's about access to weapons overall, our rights and responsibilities as citizens, and how we protect ourselves. This is a deeply nuanced problem and unyielding, dogmatic bloviating from either side won't help solve it.

As so many have pointed out, some of the most horrible shooting incidents of the past few years have been carried out by those whose who legally own guns.

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So, where does this leave us with the question of 3D-printed guns? One school of thought on gun control and the reduction of gun violence is to make it much harder to gain access to guns. While making gun access harder won't eliminate all gun violence, any added friction can reduce the problem somewhat. In this context, reducing access to 3D-printed gun object files makes some sense.

Just understand that, at least with today's technology, the 3D printing aspect of the discussion is more hype than reality. The gun violence issue in America is far more pervasive, insidious, and factionally complex than a mere discussion of a new fabrication technology.

There may be a time when 3D printing, and therefore 3D-printed weapons, becomes practical in our society. Will home-based fabrication of weapons make these numbers worse? Probably a bit. But clearly, there's a much bigger problem here.

We have a society profoundly in unrest and until we can reduce the anger, the unfairness, the inequality, the unjustness, and the wide range of familial and interpersonal problems endemic to our society, people will act out in the most horrible ways.


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