They DIY 80% complete firearms option was quite popular in CA... It used to be that you could build a firearm at home as long as you didn't intend to sell it and it was for your personal usage. Of course it also had to be in compliance with local laws (I'm not a lawyer do your own research). All that changed recently when Gov Brown signed AB 857.
CWC reports that from now on you'll have to "apply" to the DOJ for a serial number for the rifle you plan on building. Then they will issue you a serial number at which point you can build your own rifle. Btw, this also applies to rifles built in the past.
My thoughts have always been that the heavy liberal politicians will swing for the fences in terms of what they can get passed into law. While this law sucks, I'm also not terribly surprised considering that they were able to pass so many other bad laws recently.
Stay vigilant folks. I'm hoping things will get better, but it appears we've hit a bit of a rough patch these last few weeks in CA...