I'm about half way done with this helmet I'm working on and I've hit a wall. The base helmet has gaps where the ears are, and in the finished piece they've been covered with these plugs. I'm attempting to scratch build the plugs, and not having much luck. I was planning to stack three 1/2" foam exercise mats, cut off the beveled edge, and curve the back part around the helmet, then coat it with fiberglass resin. Unfortunately, in my tests the resin does nothing to harden the foam, even with fiberglass cloth added in. My original plan was to figure out a way to create a "pep file" drawn by hand on some card stock that I could fold into the shape, but I can't figure out how to do that. I've also got some pink insulation foam that I could carve into the shape, but EVERYTHING melts that foam, even regular Krylon primer. Anything I sculpt out of it will be incredibly fragile and will melt in short order. I've got sheet styrene, but not enough to stack up to the 1.5" thickness of the plug. Normally I would just bite the bullet and flush $50 worth of silicone down the drain to mold the foam and do a resin cast of each ear, but I don't know if I have the time for that whole process and the curved section in the back might make that plan impossible. I'm open to suggestions right now, can anybody recommend a way for me to do this? Oh, and I'm just talking about the basic shape of it, all those little details and greeblies will be added later. Photos thanks to Primrodo.