They were a kit-bash of sorts. I believe I used some Rowa roofs from their lightweight cars that I cut down considerably. I suppose any lightweight roof will work They may have a bit too much curve yet but they are close. The Arnold Old Timer cars are narrower so the curved edges of the roof are cut away along with any attachment tabs underneath. To attach I just used a thin line of tacky glue along the very edges where the roof meets the wall of the car but there are probably better ways for that.