Plastic has a mind of it's own when heated. It shrinks, twist and does other undesirable things. You would need to fource it to the curve you want, and then hold it there until it was back to room temp, or else it will revert to the shape it wants.Covering like monokote or orakote are examples. Try shaping a piece that hasn't been held tight by sealing itto wood around the edges.Sheet plastichas similar reactionsto heat. If you could make a positive mold of the area, you may be able tovacuum form a piece of plastic to fit.

Don