Utterly Mad

I imagine you probably could 3d print one that would work just as well as the actual commercial product, which is not at all.

you can(in the US) 3d print all but one part of a gun, and someone has made a 3d printed AR that has cycled six hundred rounds so 3d printed guns are actually viable. All of this according to a documentary I can't seem to find on youtube at the moment though so grain of salt.