On wingtips, I like to use an iron as much as possible. I weight down one end of the wing, and pull the covering while ironing. I usually take the iron on medium heat, lay it on the covering material while pulling it around the curves. As the covering material gets pulled around the curve onto the tip, I run the iron over the wood. 99% of the time, I can get the wingtip covered in 2 pieces of monokote.. the top of the wing, and the bottom of the wing. No little relief cuts, etc... just streatch it around the tip. Just remember to do it kinda quickly so you don't burn a hole in the monokote.

Hope this helped a little .. let me know if I can be any more help!!

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