I see two solutions.
One is to make a pattern that matches the bend , cut thin strips of wood and using a good glue and a lot of clamps laminate the stips. You then get a plywood like piece that conforms to the body.
The second is to start with a solid piece and steam bend it to fit, again using a wooden pattern of the curve. I have never steam bent anything "yet", but this method would give you a more original replacement.
When I laminate and probably in the case of steam bending, I use a wide board and cut the curve through the center. This gives me two conforming pieces to clamp together. And I am clamping against the square edges of the form/pattern. I would also recommend makin the pattern as thick as possible to get maximum pressure on all surfaces. I make the original pattern from card board.
