I don't need no stinkin' 3d printer (Score 1)

Given when I was younger I used to make Damascus style knives using things like farrier files and leaf springs from junk cars/trucks I think with the right tools I could make a very effective homemade firearm and until I used it nobody would be the wiser.

My point being if I were someone who was sufficiently motivated could do the same thing. I am not unique in that.

Inmates in prison, the most locked down freedom-less environment you could imagine, manage to make shanks that are lethal. A toothbrush is all it takes.

People in third world countries make knock off AK-47s and M4s with nothing more than hand tools. It is even possible to make ammunition for those weapons by hand. Of course I wouldn't want to trust my life with either one.

Stopping motivated people from making firearms is near impossible without violating other Bill of Rights amendments.