From Bearing Arms:

I’ve long argued that 3D-printed guns represent the death of gun control. After all, if the purpose of gun control is to keep firearms out of the hands of certain people–be that just criminals or, in time, everyone–the existence of 3d printers and the files one would use to make firearms means you’ll never accomplish that goal.

Anyone who wants a gun can get a gun and there’s absolutely nothing anyone can do to stop it.