In geometry, the tesseract is the four-dimensional analog of the cube; the tesseract is to the cube as the cube is to the square. Just as the surface of the cube consists of 6 square faces, the hypersurface of the tesseract
Flexagons - How to flex your flexagon! First, pinch together two triangles at a corner of the hexagon. Push the opposite corner down and in towards the center. You can now open out the middle to reveal a new face. If you can't get it to work, try the next corner.