Under Hatch Moulding (Wall Top) Question

Dear friends..
Sort of stuck here... What could I use for the wall (top) under the hatch..Cant seem to find anything that has a U shaped that will bend..
Can anyone tell me what else could be used there?
Classic Finn
Sort of stuck here... What could I use for the wall (top) under the hatch..Cant seem to find anything that has a U shaped that will bend..
Can anyone tell me what else could be used there?

Classic Finn