stuff you don't generally like.

Not your point, but why don't you like self defense? Or IDPA, USPSA, Skeet (lol), Cowboy Action, Biathlon, Hunting, or any other shooting sports?

Tbf, even in this country, guns are used far more for those things than harming others (self defense included, as while it harms others it is necessary to do so in those instances to prevent death or great bodily injury to the victim, which is what justifies use of deadly force to begin with.)

And no I disagree, if the printer allows me to print a hoffman lower at the push of a button, but that same lower would need a background check to be purchased from an FFL, I think they are similar enough to make the comparison. It's physically impossible to stop the torrents and other ways the .stl files are shared, the only way to do that would be to restrict the device itself. Furthermore a large subsect of 3d printer owners/buyers do so explicitely for the capability to print lowers (And I'm one of them. Of course it is legal for me to do so and I only use them legally, so it's fine, but still we exist.)

Of course, I think it's silly as well, but I'm also not in favor of (at least recently/currently proposed) further gun legislation, so..

Place X="cars", and Y="car related deaths and injuries", sure... I can see some hoops there making sense. Americans seem fine with the concept of a driver's license.

Yes we have those.

Place X="guns", and Y="crime / gun violence", yeah.. I can see some level of hoops making some sense.

Yes we have those too, NICs checks federally. States decide pointless feature bans or if the poors deserve rights too, and some are more permissive than others, but there are many regulations already.

Place X="3d printer" and Y="crime / gun violence"... my argument: It doesn't make much sense at all..

Actually "ghost guns," or "3d printed firearms," have been making more appearances at crime scenes as of late. The front-runner is still straw purchase but I wouldn't be surprised to see 3d printed lowers outpacing stolen guns within 10yr without even banning sales to inflate that number. Makes just as much sense to restrict 3d printers due to misuse as it does guns, since they are increasingly directly related. OR we shouldn't punish good guys with a ~~gun~~3d printer for the actions of others..

PS: There's also a third option of disagreeing with my argument, in which case you would believe the hypothetical that if 3D printing technology was removed from existence, that it would reduce crime,

There's a fourth. I don't believe reducing the number of guns nor 3d printers sold would even reduce crime, as they could instead 3d print a lower, or make a LutySMG, or mill an 80%, or buy a CNC mill, or abandon guns entirely for another weapon like the Boston Marathon. I'm a gun and 3d printer enthusiast. I think the only thing that will actually reduce crime is actually making this country better so less people want or need to commit crimes. Yes it's harder than just using authoritarian control and violence to make others subject to your will, but also fuck that, I'd rather we do the hard work than take the ineffective "easy way out."

I just also think it's silly to think "we need to ban guns because easy to kill with" but not go the step further to "and 3d printers, cnc mills, and home depot, because easy to make the thing that is easy to kill with." To me it feels a lot closer to "no further legislation needed for either."