NY bill would require a criminal history background check for the purchase of a 3D printer::Requires a criminal history background check for the purchase of a three-dimensional printer capable of creating firearms; prohibits sale to a person who would be disqualified on the basis of criminal history from being granted a license to possess a firearm.
A lot of guns use some type of plastic somewhere, there are metal parts and polymer parts. You’re going to want metal for the areas under pressure but everything else can be whatever.
You can make a shotgun with a nail and pipe from a hardware store. It won’t be very good, but it can fire shot.