There are probably hundreds of machine shops,perhaps thousands, that could make guns if they desired. I don't see why it is such a concern with 3D.
Sentiment: Strong Buy
Zip guns can be made of various materials. Look at the movie "In the Line of Fire".. John Malkovich built a gun out of wood didn't he? It would be stupid to go after 3D printer companies. Anyhow, guns are not the problem. People are!
buy a 3D printer and build a gun at home with no numbers on it no way to trace it..unreal!
Or just file the numbers off a gun bought in a pawn shop, and you can shoot it more than 6 times