As far as the receiver goes, you need a receiver with rails. Or a prebent receiver blank and rails. Or a receiver flat and rails. Do you have a drill press and good selection of drills? Can you measure, mark and drill with precision? If not, then a prebent blank is not for you. Can you weld and do you own welding equipment? If not then a laser cut flat is not for you. Do you have a hydraulic press and bending jig? If not then a non-cut flat is not for you either. Oh, and with any of the 80% receivers, flat or prebent, you'll have to weld the rails in place.
And no matter how you decide to do this you'll need a dremel tool and a good selection of tool and grinding bits for it. A vice with wood or brass jaws or jaw covers won't hurt either.
Do yourself a favor, for your first build buy a complete receiver, they're not much more expensive then blanks or flats and on your first try you'll most likely screw up at least one blank or flat. You can get a complete receiver, with the rails alreadiy installed for $60. Buy it from a gunshow or mail order and have it shipped to a local FFL that will do the transfer for you.
Next, you'll need an AK kit and enough US parts to make it legal and rivets or screws. If you buy an AMD-65 kit you'll have to decide if you're going to build a pistol or a rifle. If you build a pistol you won't need any US parts and won't need a barrel extension, but you will need a replacement piece for the rear trunnion and folding stock. If it's an AMD-65 rifle you'll need the US parts and a barrel extension and some way to permanently attach the extension and flash hider to briing the barrel up to legal length. All the other AK kits I've seen are already legal length so no extensions or welding on the barrel is needed. For US parts you'll need a US fire control group (trigger, hammer, disconnector, springs, pins, etc), gas piston, muzzle brake or hider, and rear pistol grip. This is probably enough for your rifle to make it legal, but since it's your butt it's up to you to make sure.
As far as assembly goes you can rivet or screw. Since that's a flame war waiting to happen I won't discuss it here. If you rivet you'll need tools to squeeze the rivets (and rivets, of course), you can make your own out of bolt cutters, or make a jig and use a hammer or press or air hammer. I've screwed all 4 of my builds and have thousands of rounds through several of them with no problems at all. Use grade 8 allen screws, cut them to the right length and red loctite them in. If you rivet you'll have to press the barrel out of the trunnion, usually this is pretty easy, but sometimes it's not. If you screw you can leave the barrel in the trunnion but I take mine out, it's just easier to drill and tap the front trunnion with the barrel out and you won't take any chances of drilling into the barrel. Don't laugh, I've seen it done. To make a screw build you'll need drills, taps, screws and the knowledge to use them. A cheap benchtop drill press from HF will make a big difference, assuming you can get one that has a decent chuck.
Good luck! You may want to check out gunco.com, the AK side of ar15.com, or gunsnet.net they all have build it yourself forums where you can get tons of help.
