/cgl/ - Cosplay & EGL

I like making masks and such out of fiberglass.
Problem is, I am having trouble cutting the eyes (or similiar) out cleanly.
I am currently using a small drill bit for a Dremel to cut them out, but as you can see in the pic, the cuts are anything but clean.
What would be a good way to clean the edges?
A sanding drum on the dremel doesn't seem to take off enough material, and when you apply too much pressure, it just makes little round notches, making it all worse.
Any insights?