The Klein bottle was discovered in 1882 by Felix Klein and since then has joined the gallery of popular mathematical shapes known to the general public outside the "ivory tower". The bottle is a one-sided surface - like the wellknown Möbius band - but it is even more fascinating, since it is closed and has no border and neither an enclosed interior nor exterior.

https://plus.maths.org/content/imaging-maths-inside-klein-bottle

https://en.wikipedia.org/wiki/Klein_bottle

Video tutorial: https://youtu.be/IcKBiqO1uQY