I don't get it - afaik you can get every single part of a gun except for the lower receiver/pistol frame without any restriction - as those parts are legally defined as the 'gun' - the rest are just replacement parts.

Even for those, you can get 80% finished parts for those - just drill a few holes, and file off some tidbits, and you get an almost factory-spec gun.

I'm no expert on US gun law, but afaik, some states even allow you to make your own guns without registration, as the law defines gun manufacturing as manufacturing with the intent of selling them.

So there's plenty of options, many of them better than making a gun with a printer.

But even all this is typically overkill, I dont think criminals go to these lengths to make their own guns, they just get them from somewhere.

The only usable part a plastic 3D printer will make for you is the receiver, which is the whole point, to circumvent that very narrow legal classification. You're right about alternative lawmaking avenues, but given the 2a pushback on controlling "replacement parts" Americans are kind of stuck with the bed they made.

The receiver is like the asset tag on computer servers- it's the one thing that is definitely not replaceable since it has the serial number used for entitlement.