Kaleidocycle
A kaleidocycle (or flextangle) is a flexible polyhedron connecting 6 tetrahedra (or disphenoids) on opposite edges into a cycle. If the faces of the disphenoids are equilateral triangles, it can be constructed from a stretched triangular tiling net with 4 triangles in one direction and an even number in the other direction. The kaleidocycle has degenerate pairs of coinciding edges in transition, which function as hinges. The kaleidocycle has an additional property that it can be continuously twisted around a ring axis, showing 4 sets of 6 triangular faces. The kaleidocycle is invariant under twists about its ring axis by , where is an integer, and can therefore be continuously twisted. Kaleidocycles can be constructed from a single piece of paper (with dimensions ) without tearing or using adhesive. Because of this and their continuous twisting property, they are often given as examples of simple origami toys. The kaleidocycle is sometimes called a flexahedron in analogy to the planar flexagon, which has similar symmetry under flexing transformations. (Wikipedia).
