[testbro]

Given that all a 3D printer will produce is plastic (ignoring SLS as it's much further away on the radar), the number of shots is limited before it fails. That's in addition to the requirement to buy ammunition first. Something from Home Depot probably poses a greater threat and would be equally undetectable.

I can't imagine anyone opting to buy a printer, calibrate it and print a terrible gun when they could just buy a hammer (or improvise a firearm out of a piece of pipe).