Shaped the .050" doublerswhich go on either side of the fin, determined the location of the 1/4" bolt hole matching it up with the frame. Then I decided on the rivet pattern. I decided to use aircraft flush rivets and use my new hand squeezer to set them. Had to anneal my rivets, because they had hardened over the last years to a state too hard to squeeze. Installed all rivets. next I made another wood plug for the horizontal fin.