I'm thinking (that's usually dangerous /ubbthreads/images/graemlins/jester.gif) that you could make a perimeter frame with either the 1/8th inch hardboard, or 1/8th inch ply/panelling wood, and then mold a fiberglass one by stretching a fleece cloth over the frame and letting it sag (upside down) with the resin in it while it dries... then you can cover it with your material of choice: cloth, vinyl, paint, whatever. But I'd probably rather buy one if they are available somewhere... fiberglassing is messy and you'd probably wind up spending nearly as much money. Modern car headliners (the one in my wifes Talon anyway) are made of thermo-moulded foam, and covered with the same thin foam and cloth... the foam cusion dryrots with heat and age, making the cloth sag. I covered hers with black vinyl... looks pretty good too.