Sounds like you may have discovered a niche. If it were me, I'd probably take a camera with me to an auto swap meet, or local body shop where 'in-progress' fiberglass work might be seen. Then snap some good close-up images of the repair work you like, download them onto your computer, (manipulate with Photoshop, if necessary), then print them on white decal paper. Voila! You've got scale fiberglass. You'll probably need to provide some texture to the area on the model you're looking to do your 'glass work'. I'd suggest a thin application of filler then lightly drag a bristle brush across the filler in a cross-hatch fashion. Good luck sir, let us know how you come out.