Klein bottle, 1995.
© Science Museum / Science & Society Picture Library
A single surface model made by Alan Bennett in Bedford, United Kingdom. It consists of a parallel-sided coil with remote return tube with the inlet and singularity at the same end, which when theoretically cut gives a pair of 17-twist Mobius strips. A Klein bottle is a surface which has no edges, no outside or inside and cannot be properly constructed in three dimensions.