ORIGINAL: opjose
A minor tip...
Once you've started an opening or hole, and are nearing the final sanding, apply thin CA to the inside of the cowl around the area that you are working on.
This will prevent cracking and help to strengthen the areas you are cutting into. It will also eliminate fiberglass "hairs" in the cut out areas.
Excellent tip! I will have to add this one to the note book.