With the AWB dead, the main laws you need to make sure you comply with are the NFA and 922(r). As long as your AK is not a machine gun, has a barrel length of at least 16", and an overall length (with stock folded) of at least 26", you should be good for NFA purposes.
922(r) is a different story. As long as you have 10 or less foreign parts on your rifle (parts from the BATF list), then you have a "US made" rifle and it doesn't matter. Most of the commercial AK's being sold today are 922(r) compliant already, so it's a non-issue. But for guys who home-build their AK's from parts kits, you have to make sure you're compliant. Once 922(r) is satisfied, you can go hog-wild. Folding stocks, hi-cap mags, bayonet lugs, etc.