My friend and I made our own headliner for a '73 Dart Sport from Centra plastic. It's a plastic sheet used in signmaking, comes in 1/8" thickness or a little thicker. Seems to me we had the thicker stuff and wished we had the thinner stuff. We used the cardboard as a template and made the new headliner in 3 pieces, then glued modern headliner felt to it. Looked pretty good.