Any home built firearm HAS TO conform to ALL laws. So, you can not build any NFA type weapons. As long as it isn't NFA you can build and possess it. The only caveat to this is if you build an AR15 in California (or other restrictive state) the home build must comply with the laws of that state, ie. Bullet Button, 10 round maximum capacity, length requirements etc. Serial numbers, maker's name and caliber identifications are NOT required however they are recommended. Home builds can be sold. The wording is quite clear on this but less clear on the number of home build weapons that can be built and sold. Basically the wording states you can't do it for profit.