Wow, that's too far gone to make a mold and cast a replica. You might have
to make a new one out of wood (or whatever) and paint it. What do
modelmakers use -- balsa? Foam plastic?

A long shot, but I wonder if this could be re-bent if you heat it with a
heat gun. Many old plastics (including the dreaded Tenite) won't re-soften,
but you haven't got much to lose.

Phil