Again my warning: THIS IS NOT A GOOD DRINKING GLASS! It’s difficult to get liquids in. Difficult to get liquids out. It’s difficult to clean. (it’s also difficult to make, if that’s any consolation. ) Please treat it as a mathematical curiousity rather than a practical cup.
I prefer my coffee in a Klein bottle. I only drink ∞ a day
Do you want small, moebius or large?
https://www.kleinbottle.com/drinking_mug_klein_bottle.htm