I absolutely do not think the ability for people to manufacture their own guns has any bearing on any of this. Gun nerd forums are rife with people observing that a full-auto conversion isn't rocket science either, and the immediate responses are always "you'll go to prison for 10 years". "Printing" has nothing to do with it. Computer nerds didn't invent machining.

You can already build a gun with entirely legal machine shop tools - like the brit Philip Luty's submachine gun [1]

Luty was arrested with the gun and ammunition and -quelle surprise - jailed for possession of an illegal gun.

[1] https://www.youtube.com/watch?v=sIhGCRIQnCA