Does anyone know the additves which make a resin matrix flexable. My customer has changed the final color scheme of the part and I already have the yellow/black carbon fibre. So the fender is going to be mostly white with parts of the yellow/black carbon fibre showing. I just dont want the paint of the gel coat to wind up with spider cracks in the finish. Need some help guys. Thank you all for your help in advance 
I have told Evan about a local supplier that has a flexible PER resins.
Yeah it’s a polyester based resin and it’s very flexible. I can only get them in 5 gal pail. If you want to use epoxy, I’ll look into it. There’s no additive, you just have to buy the specific resin with that characteristic.
So it’s actually a different resin and it’s Epoxy. Okay that changes everything I guess. I never worked with Epoxy. I can still use a poly mold, right?
No there’s both
Why not you a urethane?