We lost the ability to print $50 bills with our HPs[2] and it had no noticeable negative impact on society. I'm not sure why losing the ability to print a gun with our Prusas will be any different.
[1] - https://www.scienceabc.com/eyeopeners/cant-photocopy-scan-cu...
[2] - https://h30434.www3.hp.com/t5/Printers-Archive-Read-Only/Won...
I doubt there is a weapons expert that could look at a given STL file and unambiguously tell you whether something was “part of a gun” or not. If these laws pass, they will be either unenforceable, effectively ban all 3D printer sales due to the immense difficulty of compliance, or worse, be another avenue for selective enforcement.
Furthermore, the whole “ghost guns” thing is entirely overblown and misunderstood by people who have never seen or used a 3D printer except in the movies, where Hollywood has latched onto the idea that they are designed primarily for making guns. A consumer grade 3D printer is going to print a gun that will explode in your hands the first time you try to use it, if any of the meaningful parts of the gun are printed. And nothing is stopping people from say, fabricating gun stocks with a table saw and router, or building a gun out of hardware store parts. Why aren’t we also banning mills and lathes while we’re at it? There are also chemicals at a hardware store that could be used to make explosives. If the concern was really “making guns at home”, we’d outlaw Ace Hardware and Home Depot.