If Klein Bottles - which have neither an inside nor an outside sur...  ...en't confusing enough for your, check these glass Klein bottles made by Alan Bennett for the Science Museum in L...  ...in Bedford, United Kingdom. It consists of three Klein bottles set inside each other...

A Klein bottle is "a closed surface with only one side; formed b...  ...ning it with the other end." Pictured above is a bottle opener shaped like a Klein bottle . It was made by Bathsheba Grossman, who explaine...  ...ned: The problem of beer That it is within a '...