I have seen this before, there were some guys in Texas that did the same thing. They printed a bunch brought in a box and made off with $8k and only cost $200 in PLA plastic. It's a loophole, they can't deny you because a gun is technically classified as something that fires a round. Same thing happened another time, kids bought pipe, and made a real crude nail striker pin and were able to shoot a shotgun shell out of the tube, like an old blunderbuss, and they made out good as well. They can't say no, because then they say "You don't want guns off the street"?