That's not actually true. 3D printers are additive manufacturing, i.e. you build up from nothing. Most hobbyist tools are generally subtractive manufacturing, i

That's not actually true. 3D printers are additive manufacturing, i.e. you build up from nothing. Most hobbyist tools are generally subtractive manufacturing, i.e. you start with a block of raw material and remove sections with the tool. Additive manufacturing allows you to make some parts that are impossible with subtractive manufacturing. That said, you can make an entire gun using subtractive manufacturing, pretty standard metal, and a CNC mill. If we had a standardized library of CNC mill instructions you could just as easily share that as a STP file for 3D printing a gun.