Here's how a rational attempt behaves
FWIW
http://www.thefirearmblog.com/blog/2014/11/04/warfairy-charon-3d-printed-ar15-lower/
A set of G-code files for a proper gun made from common stock materials would be far more meaningful than the plastic fantasy crap. CNC machine tools are in the same price range as plastic 3D printers.
Good 3D printed guns (e.g. the sintered stainless steal 1911) are possible, but only as a stunt. Production costs and labor are ridiculously high relative to normal production processes.