There are several people laboring to create working firearms with their 3D printers, including one ambitious effort to make the whole thing from scratch. But so far, only one person has managed to produce firearms that actually work. A gunsmith known only as HaveBlue produced a working AR-15 lower receiver and fitted it to a pre-existing barrel. It test fired 200 rounds beautifully. Sure, the metal firing pin and barrel weren’t 3D printed, but it’s only a matter of time before making a gun is easier than buying one.