Ever seen them? Ever heard of them? Yeh. I have some now. We stopped at a garage sale and I found this little treasure buried in the games. It is from Kling Industries. Google it, they are still around and it's really expensive. The one I have is apparently one of the first they made. I will post some pics after I get batteries for the camera ..... again.
Haven't really tried yet, they are rather dirty. I was going to attempt to clean them somehow then see. It seems to be a thin metal sheet, covered in paper.