Not being picky, but I would guess that you're looking for Nuts and Bolts.
They are far easier to source as you are commonly looking for specific lengths and the size of the hole that the bolt needs to pass though. I would recommend that you consider nylock nuts as it is much harder for the Parrots to remove them.
Hmmm, it sounds like you're looking at something that is laying in large sections on the floor or against a wall. I would strongly recommend that you attempt to place them together to assure you have the right sections. Assure that the holes match-up! Take a package of zipties and a knife to cut them off. This will allow you to test assemble the sections.
