There seems to be some idea that firearm manufacturing is some version of witchcraft when the reality is that it's closer to the professor with his coconuts on Gilligan's Island. The arguments tend to go something like: "That's impossible" when actually it really isn't. "That's illegal" when not only is it not, but it's specifically protected. "You shouldn't do that" when some people just like to tinker. "That should be banned" without understanding that the regulatory framework to truly ban it would require tracking everything and every one at all times.

That last one is where you get into a lot of very hairy issues. Apps to track women's periods have been datamined, and some states propose using the data to look for possible pregnancies and termination of pregnancies. You can track every purchase of barstock, milling machines, routers, tampons, router bits, buckets, bags of salt, car batteries, and every web page access, and you'll still not stop it, but the amount of privacy you lost in trade for the attempt is staggering.

The best comment in this thread, by far, is this one as a proposed solution to the problem, but of course nobody wants to try that. Instead we want to throw regulatory spaghetti against a wall and demand that people accept less durable materials to work with or demand that people be less innovative. History suggests those approaches won't work.