Lipson also doesn’t believe criminals or those who would use the guns for sinister reasons would print one instead of simply buying a cheap conventional handgun. But even a working pistol that will fire enough rounds to kill someone could be enough to break gun control at the sale point — skipping around rigorous background checks and restrictions on high-capacity magazines.

“Criminals have other channels to get guns, but I am really more concerned about hobbyists and enthusiastic kids trying this route at home and actually injuring themselves in the process of doing that,” Lipson says. “If you make one and got it in the wrong temperature or was shoddy in any way, it’s actually dangerous to fire.”

This is a problem for Defense Distributed. The group has been cautious to note that “melting and failing in your hand will be a concern,” according to the group’s website. Hence the need for a lot of testing.