Always good to finish up with a rounded Bastard file.

If Roto zip bit breaks be sure to have something below you because it will burn carpet, I know first hand.

Have used rotozip for many holes in the boat..works better than great

Thanks for all the help. Audiofn I will only being cutting through glass. I think I will try the Rotozip. By the way were in the word can you get a holesaw that big?

at the ho saw store

don't forget to reglass the exposed edge west system is always good for that

If you use a jig saw, use the reverse pitch blades. They cut on the down stroke reducing the chances of chipping the gel coat.