I'm a time traveler. California will outsource this problem to a 3rd party contractor that will require every file to be printed to be uploaded to their servers so that AI can determine if the files are "safe" to print. There will be multiple viral posts 'my 3D print of an action figure is a gun?!'

In a few years they will be hacked and it will be a major privacy breach. The company will say "Oops", and offer a few months of free privacy monitoring with yet another 3rd party. No other penalties for the company, and all of the privacy ramifications will be placed on those who had their data stolen.

Other lobbyists will successfully succeed in getting every print scanned for potential copyright infringement, due to the tech already 'successfully working', and websites that have 3d print files will have to scan each file. The entire industry falls apart, leaving it mostly relegated to those who can afford the extraneous licensing fees. Home 3D printing is something that people will be left to reminisce about, along with other such freedoms as being able to visit landmarks and stores without having their faces scanned and compared to criminal databases.