I use lite weight cloth and resin or just epoxy, get the cloth from LHS or Tower.... I usually apply around any cutouts , mounting screw holes, or any damage, cut the cloth to fit and you can hold it in place with small amount of CA then brush 20 or 30 minute epoxy or resin over cloth and work it in good.... I use to do lot of glass work on Corvettes and semi truck hoods when I use to do body work, same principle.... Clean cowl with laquer thinner or alcohol before repair... If your doing repair to the outside painted areas you will have to sand through the paint and gel coat before glassing over the damaged area, glass and after it cures, sand it and feather it in with surrounding area, a little bondo works well also, prime and refinish..... You can do a search on RCU an find lots of tips on glassing and refinishing. Larrry