It also requires a good amount of knowledge of chemistry, and you (personally) building a rig you use solely for the purpose of making meth that is itself highly prone to detection.
Meanwhile, printing pieces of a gun does not require specialized knowledge, nor machinery, nor even putting yourself in any sort of extreme danger. 3D printers are general use by their very nature.
Democratization of technology; it’s a scary thing. Eventually, it will make most forms of prohibition pointless; but for right now, certain drugs and automatic weapons aren’t among the things you can reliably make. Certainly not at a price point that’s less than a decent laptop.
No, that’s a different sort of policy entirely.
Gun Free zones do not control who owns a gun; only where you can take them.
If you want to ban people from taking Bump stocks somewhere, you may be able to do that. It’s far more difficult to prevent them from having one in the first place, because then, you’re trying to control what people do at home.