Kaleidocycle!

Have you ever heard of a kaleidocycle?  It is a ring made up of a number of tetrahedra.  A tetrahedron (plural tetrahedra) is a polyhedron composed of four triangular faces, three of which meet at each vertex.  It's like a 3-D, three-sided pyramid.  My kaleidocycle is made of eight  tetrahedra connected on perpendicular edges.  What makes it special is that you can continually twist it inwards or outwards while it shows different sides of each tetrahedron. 

Too see this piece in action, see:  http://www.youtube.com/watch?v=UNaE6nlruCE