All AN hardware is included in the kit. Unless you lose something, you shouldn?t need to buy extra. That said, I have some extra bolts in the more common sizes that I sometimes use for test fitting, just to prevent the stuff I?ll use for final assembly from getting too scratched up or damaged.
I also have some non-locking nuts I sometimes use for trial fitting. You don?t want to be using the elastic stop nuts too many times, or they won?t hold as tightly as they will when they are new.
Oops rivets aren?t included. Since most of the rivets in the -12 are pulled rivets, you probably won?t need Oops rivets. Oops rivets are for replacing an occasional flush-head solid rivet that you might mess up when riveting skins. In the -12, the skins are attached with pulled rivets.
In the places where you use solid flush-head rivets, you?ll be using a squeezer, not a rivet gun, which also minimizes your chances for needing oops rivets. Finally, most of the solid rivets in the -12 are AN-470 (universal head) rivets. If you goof these up, you can?t replace them with an Oops rivet. You can carefully drill out the rivet and try squeezing it again, or buy new parts. In some cases, you might be able to use the next size larger rivet, but it depends on location, edge distance, etc.