Built up my blocks for bending the elevator tab with some scrap cherry flooring. One block with one cut creates the dies needed. I used double sided carpet tape to help hold the blocks against the inside of the skin per the plans. Clamped it up on the side of the table and used a hammer and wood block to start, and then finished up with the flush set in the rivet gun turned down low. It wasn't perfect, but good enough for me. Small imperfection at the edge of the block. I would recommend using something thicker then the 1 by flooring I used to avoid this.
