Thin fiberglass is flexable. Thin fiberglass on a curve isn't.Thick fiberglass is flexable if it is flat.
Resin may not be flexable IF it is thick, but it is very very brittle. Not good. You HAVE to add mat or cloth, or even some fleec, cotton, poly material to it. Any of that is better than just resin puddles.
Resin soaked fleece IS flexable. But it will crack. Adding 1/3" thick resin on it isn't doing anything but making ut heavy. It will still crack.
YOU HAVE TO ADD SOME TYPE OF FIBERGLASS MAT OR CLOTH.
If you want to do something in a material and not add mat to it, try unbacked carpet. It comes out **** thick. But only for cosmetic reasons or non stressed parts.