'Way-in-way-out vesel', 1995.
© Science Museum / Science & Society Picture Library
A single surface model made by Alan Bennett in Bedford, United Kingdom. This 'way-in-way-out vesel' is equivalent to two Klein bottles, one inverted, sealed together back-to-back. When cut it forms two pairs of single 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.