yakherder
老外
I saw an article somewhere where some guy had found a way to make a gun (pistol) with a 3-D printer. (He was a libertarian who thought everyone should be free to have a gun.) I think there was one part of the gun that the printer could not make, so you had to buy that separately. But apparently buying that part did not require any of the gun registration or licensing that buying a regular gun would involve.
Actually I think the firing pin was that one part. He used a standard nail as the firing pin. But that's only now, and will not be a problem in the near future when commercially available 3d printing isn't limited to plastics.
Some guy was already arrested in Japan for printing revolver parts.
If they're already printing organs with 3d printers that basically use stem cells as ink, I'm pretty sure they'll get simple metal objects figured out.