I'm slightly ahead of you in the building process of the Artic Tern. It doesn't take long to sand off the excess epoxy from the panel edge. I used a sanding block & coarse sandpaper and in just a few minutes had sanded off about a 3/16 inch wide fully cured epoxy overrun on the panel edge. It was pretty easy & went faster than I thought. I held the panel on its side & sanded vigorously until I neared the actual panel edge, then was more careful & gentle to avoid sanding into the panel.

I also put a piece of clear plastic (a Ziplock bag, actually, since that was handy) between the mylar & my plywood (since the scrap wood I was using was wider than the mylar.) It prevented the accidental gluing of the scrap wood to the panel. It worked great. Epoxy won't stick to plastic wrap. I put a layer of plastic under the panel, too.

Julie Kanarr