3D-printed guns may be more dangerous to their users than targets

Despite fears that guns made with 3D printers will let criminals and terrorists easily make untraceable, undetectable plastic weapons at home, my own experience with 3D manufacturing quality control suggests that, at least for now, 3D-printed firearms may pose as much, or maybe even more, of a threat to the people who try to make and use them.

A company called Defense Distributed developed a 3D-printed gun called the Liberator, which many fear could pass through security checkpoints undetected. AP Photo/Eric Gay Sen. Edward Markey, D-Mass. and Sen. Richard Blumenthal, D-Conn., display a photo of a 3D-printed gun. AP Photo/Matthew Daly
One firearms expert suggested that even the best 3D-printed guns might only fire “five shots [before] blowing up in your hand.” A weapon with a design or printing defect might blow up or come apart in its user’s hand before firing even a single bullet.

As someone who uses 3D printing in his work and researches quality assurance technologies, I’ve had the opportunity to see numerous printing defects and analyze what causes them. The problem is not with the concept of 3D printing, but with the exact process followed to create a specific item. Consumer 3D printers don’t always create high-quality items, and regular people aren’t likely to engage in rigorous quality assurance testing before using a 3D-printed firearm.

Problems are common at home

Many consumer 3D printers experience a variety of glitches, causing defects in the items they make. At times, an object detaches from the platform it’s on while being made, ending up lopsided, broken or otherwise damaged. Flaws can be much harder to detect when the flow of filament – the melted plastic material the item is being made from – is too hot or cold or too fast or slow, or stops when it shouldn’t. Even with all of the settings right, sometimes 3D-printed objects still have defects.

Some 3D printing defects are easy to see. Others can be far more difficult to detect. Jeremy Straub, CC BY
When a poorly made toy or trinket breaks, it can be hazardous. A child might be left with a part that he or she could choke on, for example. However, when a firearm breaks, the result could be even more serious – even fatal. In 2013, agents from the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives tested 3D-printed guns and found that the quality of materials and manufacturing determined whether a gun would fire multiple rounds successfully, or break apart during or after the first shot.

Home printing also risks that nefarious people might tamper with the design files on a website, publish intentionally defective designs or even create a virus that interferes with the operation of a 3D printer itself. Hackers may deliberately target 3D printed guns, for ideological or other reasons, or inadvertently cause defects with more general attacks against 3D printing systems.

Not up to commercial standards

Commercial manufacturers of guns double-check their designs, test models and perform rigorous examinations to ensure their firearms work properly. Defects still happen, but they’re much less likely than with home-printed weapons.