Making small fiberglass parts...

Step 9:

Traditionally, fiberglass parts are coated with "gel coat", a wax rich polyester resin.
Gel coat is thick, heavy and brittle, so it doesn't take a lot of it.
But it provides excellent protection against UV damage from the sun.

It goes on like thick paint, and cures in a few minutes.

Once WELL cured, it can be sanded smooth (start about 220 grit for shaping
and 400 for smoothing. 

Lastly a touch of polishing compound on the buffer and - it's ready to go to work.