Well.... This is interesting, the plans say that the flaps are the "easiest" control surface to build. I beg to differ with that acessment as they really don't give much direction on the final assemby process / rivet order. They basically just say to rivet everything inside prior to "closing the door with the spar. I was having a bit of anxiety over this assembly. I conned Peter into coming over and giving me a hand. It was much apprecited bucking help. we did manage to put a nice ding on the bottom of the flap. Ugh! We worked out the dent as much as possible. I'll touch this up with some micro later on when I get the fiberglass stuff back out.