As willyswagon said, the kit, reciever, US compliance parts, and rivets (or screws). AKs need 6 total US made parts to count as US made. Standard sets of parts are FCG, gas piston, and muzzle brake (or pistol grip).
Tapco has a decent deal on a parts set and FCG or there is decent deal running on FalFiles by bocefus. tons of places out there with parts, average running price is ~100 for the kit, 30-35 for the FCG.
Willy, you mentioned bending some flats to make recievers, do you have the bending tool?