Well, this will sit at the output of the spirograph, meaning it has to be able to bounce a spirograph pattern off it, not just a straight and steady beam. A lens or anything like that won't work in that situation. A mirror from a barcode scanner could work,
but seems like they're very flat, so wouldn't be able to accommodate a spirograph pattern, which is why 1" tall or so would be desirable. I might attempt to glue mirrors on something from ebay, if I can't find a suitable mirror ready made. Even a mirror from a barrel mirror scanner could work I guess, though might be a bit bigger than what I need. Still, bigger is better than smaller....