Cliff, if you're still hanging around the thread, I want to thank you for this Klein bottle I got over a decade ago, back when I was a mere math undergrad. [1]

Cliff, if you're still hanging around the thread, I want to thank you for this Klein bottle I got over a decade ago, back when I was a mere math undergrad. [1] Despite a number of close calls and myriad stories about strange objects getting trapped in it, it's maintained its structural and multidimensional integrity over the years. Thank you again! [1] https://i.imgur.com/vlkIcKu.jpg https://i.imgur.com/vlkIcKu.jpg