Flexagon
Paper model / From Wikipedia, the free encyclopedia
In geometry, a flexagon is a flat model, usually made by folding a piece of paper, so that when 'flexed' (folded), one or more hidden faces will be revealed (shown) from within the model.
Flexagons are usually square or rectangular (tetraflexagons) or hexagonal (hexaflexagons). A prefix can be added to the name to show the number of faces that the model can display, including the two faces (back and front) that are visible before flexing. For example, a hexaflexagon with a total of six faces is called a hexahexaflexagon.