For reasons that aren't entirely clear to me, firearms manufacturers seem to think they're entitled to instead stomp their feet and say "no, no regulation, you have to let me do whatever I want!". I'm never quite sure why they think this foot-stomping would be at all persuasive to people who don't manufacture firearms. Again, I imagine you don't see things this way and I'd be happy to learn more about what I've gotten wrong here.
Go solve gun crime with boots on the ground instead
It's incredibly bizarre that you feel entitled to issue commands about what I or the California legislature must do instead of passing the regulations you don't like. What is your mental model of the world, where someone would read the words "Go solve gun crime with boots on the ground instead" and not become more passionate about the idea that we must regulate you whether you like it or not?
I 3D print as a hobby, mostly items related to retro computing/gaming and things like Gridfinity storage boxes.
But I value my privacy, and don't want governments scanning my models before I'm able to print them, just as I wouldn't want them scanning my code before I'm able to compile it (these days, code can potentially be a weapon of war, malware or drone flight controller code being more powerful than a plastic gun)
Who exactly is the "firearms manufacturer?" I've owned and used 3D printers for years. Not once has anything I've used or seen from any 3D printer manufacturer or other related supplier have anything to do with guns.
Why do you think they would be opposed to this? (I doubt they care.)