Have you tried clecoing any of the skins to the frames yet? When I was first putting my tailcone together, I was looking at the frames like they were ribs and wondering how to get them flat and with flanges at 90 degrees. Turns out the geometry was such that they were pretty close to perfect out of the box (they aren't supposed to be flat), just it didn't seem that way laying on the table--they looked warped to me. However, once installed all I had to do was flute where directed (on the -10 you flute every tab with 2 holes) and all holes in the frames and skins aligned with minimal fussing around. I didn't have to seam a single tab.