The actual bill in question: https://leginfo.legislature.ca.gov/faces/billNavClient.xhtml...
It seems more precise to say that 3D printers sold/transferred in California would need built-in anti-firearm-printing controls?
I don't see how this directly bans students/teachers/businesses from owning 3d printers, which is what the title seems to say.
It does not. The gun lobby routinely lies about California regulations to try and get their way. They're on year 13 of boycotting the California handgun market, for example; new handgun models in the state are required to adopt microstamping technology, but firearms manufacturers are ideologically opposed to this technology, so they falsely claim that it doesn't exist.