While that’s true, you can also get access to 3D printers without actually buying one. Friends, local maker spaces, etc. I would be unsurprised to find some enterprising organized-crime types buying some nice printers and setting up shop to provide unregistered, untraceable firearms to their buddies.
Having said all that, I don’t think any of the current government attempts to nip this gun-printing in the bud are a good idea. They won’t help against big crime anyway.