This is just the latest attempt to distract California citizens from something else that is going wrong in California.
As I've pointed out in other threads there are no laws in the USA that prevent someone from making a gun from scratch. If you can legally own a gun, i.e. your not a convicted felon, underage, etc. you can build on for yourself. It has to be within the existing law regarding barrel length, over all length, can't be full auto, and you can't sell or otherwise transfer it to another.
A trip to the hardware store and about US$25 is all someone needs to build a functional gun out of pipe fittings and a spring. No 3D printer needed. I'm actually surprised no one has made a hybrid pipe fitting firearm with 3D printed parts. It would be much safer than the current 3D printed plastic toys they are trying to ban.
https://en.wikipedia.org/wiki/...
https://www.criminaldefenselaw....
And an interesting bit of trivia;
In the USA the cities with the most restrictive gun laws also have the highest incidences of gun violence.
Sweden has almost he same per capita gun ownership as the USA but only a fraction of the gun violence, or even just violence in general.
America is violent at a cultural level, if you want to reduce gun violence then you need to focus on reducing violence as a whole.
Ban guns, people will use knifes (remember the UK trying to ban steak knives?), take away the knives they will use cricket bats, skillets, pipes, tree branches, etc.
The core issue with gun related violence is not the guns, they are just inanimate tools, but the culture that considers the use of deadly force to be an acceptable first response instead of something to be avoided at all costs. Fix the cultures and the violence goes away.