Open source guns are great. But in my mind the number one thing people need to be working on is the propellant. California is a glimpse of the future and they're starting to restrict ammo just as much if not more than the actual firearms itself. You can't buy ammo unless you have a registered gun in that caliber inside of California. If you have a source for black market ammo then presumably you have a source for black market firearms as well as it's really not too much of a stretch between those two things.
The revolution has machinists, and it has 3D modelers. What we need next are chemists, real chemists.