One of these was given to me as a graduation gift. Included with the order receipt were photos of him wrapping up the Klein bottle, holding it up and smiling with it, and the receipt was signed with a note saying, "Congratulations!" It's possibly the best present I've ever received! In case you see this, thank you Clif!
Because of this I read The Cuckoo's Egg, and it was pretty great too. What a cool guy.