I drilled the trapdoors and hinges for the rivets, I deburred the rivet holes. I had deciced to dimple the hinges, as the metal was soft, and I didn't expect any deformation, and so it proved. I also dimpled the trapdoors and then riveted them together using 3-4 rivets. I then drilled the rivet holes in the hinges and the ribs, and clecoed them together.