During our Jayco pop-camper restoration, we needed to repair the 4 corner caps on the body of the camper. These caps protect the corners when the camper’s roof is in a fully closed position. The caps overlap the trim, and they cover/protect the inner wall which would otherwise be exposed.
Our caps were dry rotted and cracked in multiple places and didn’t sit level with the surface.
Our solution was to coat the caps in several layers of fiberglass resin. Once the corners were cured, we applied two coats of white epoxy appliance spray.
This method would work for most plastic trim fittings that need to be repaired or replaced.