Fiberglass is easy, just patience. Oh and resin gets ya a good high.
So do it in a ventilated area. Used either a fine grit or worn down angle grinder pad and rough up about 4" on either side of the cut. Both inside and outside. Careful not to go too deep or you'll burn through. Mix up the resin and soak strips of glass in it. Lay thin strips at angles. Let the first layer dry and start laying them overlapped. Dont build up to much though unless you dont care about the looks or you'll have a big bulge. I can help ya if you want. I've redone a fiberglass cowl induction hood before. It was tore to shiat and I made that thing show quality smooth again. Not boasting or anything but the painters at the body shop were impressed.
