Here’s glassblower Alan Bennett’s astounding triple-nested Klein bottle, a beautiful thing:
A single surface model made by Alan Bennett in Bedford, United Kingdom. It consists of three Klein bottles set inside each other to produce, when cut, three pairs of single-twist Mobius strips. A Klein bottle has no edges, no outside or inside and cannot be properly constructed in three dimensions.
[From user winkybb: Theoretically, with a Klein bottle the “tube” passes through the side of the bottle without there being an intersection in the surface. The tube passes from one side to the other in a fourth dimension. Not possible in three dimensions, so this is a representation only. Not a true Klein bottle.]
(Image: Science Museum/Science & Society Picture Library)