Dr Stoll was _incredibly_ friendly during the process of buying all of these (I tried to keep it organised but I did ask him to send eight different packages to something like eight different locations!) and I bought his smallest-model Klein bottle for myself at the same time. It and its accompanying propaganda is one of my prized possessions, sitting on a shelf next to a wild boar's tusk, a 1920s brass charting compass, and other Really Cool Things.
If you read this and happen to remember me, Dr Stoll, I'm very grateful -- plus, I have no idea how to top that gift for my team next time we have a new release out. The next one is later this year. How can I do better than that? I genuinely don't know what to get them next :)
If you're interested, this is his website: https://www.kleinbottle.com/ It has far more than just normal Klein bottles. There are Klein hats. Klein earrings. Klein Erlenmeyer flasks...