Your thread title made me think of Möbius scarves. Maybe not what you had seen but a fun thing anyway and they're great for the math geek in your life!!
There's a great intro to the cast on here
on YouTube and the same lady has a free pattern for a full scarf here
. If you Google Mobius scarf you'll find lots of pictures of lovely examples, too.
If you're not failiar with the idea of a Möbius here's