Okay, my 68 Fastback is missing some of the parts for the fold down rear seat. I have seen full sets on Ebay for 400-600 bucks. Has anyone attempted to remake this with plywood (the part I'm missing is the one that covers the front of the seats (closest to you when looking back).
Since it has chrome trim around the edges, I don't think a wooden replica will look too cool unless you remove it from the other pieces as well. Have you tried to find just the piece(s) you need on ebay or Mustang classifieds? I think I happen to have the one you described lying around... pm me if interested.