Usually when I encounter a problem I'm not sure how to fix, I stop and scratch my head for a few days about it. I find that my brain likes to let things percolate for a few days before spitting out an answer. I could not for the life of me figure out how to cut the aluminum wingtip sheet to the correct size. I couldn't see the tangent lines I had previously marked on the wingtip flanges, and every time tried using my edge marker, it didn't work. My solution was to make a template out of 1/8" Plexiglass and attach it to the wingtip. This way, I could see the tangent lines and use a ruler to mark short segments to make up the curve. It worked like a charm. I was able to make up a template that not only gave me the tangent line spacing I was looking for, but allowed me to make sure that edge distances were observed, and no rivets ended up on crimp lines. Although I've put a lot of time into this wingtip, I'm very pleased with the outcome.