Well, I bought a Klein bottle and knitted Klein hat after seeing that talk many years ago, so it wasn't entirely useless :-)

I still have the hat. I no longer have the bottle as I moved to the other side of the world a number of years ago, and after inquiring with some mathematician friends it turned out that four-dimensional glass bottles are not compatible with three-dimensional backpacks :-/

When I got the package it was covered in hand-written notes; gosh, I don't remember what it said exactly, but it was hilarious; somehow you even managed to put some joke in Dutch on it. I wanted to email something back but I was shy and didn't know what to say. So, about a decade too late, thanks! Not only was I very happy with the bottle, the packaging absolutely made my day all those years ago.

I saw that talk a long time ago, but I can still hear you saying "I would dearly love to talk about one-sided objects!" I appreciate your infectious energy.

I just watched this for the first time. Your energy is infectious and inspiring.

Thank you for what you do.