I have a simpler example and I see that its idea is similar to the above one. ![Example of a polyhedron][1] Cut the vertices of a cube to form 8 small triangles and suppose the triangles are rigid but the faces are not. Then rotate the triangles, 4 of them clockwise and the rest counter-clockwise, in an alternating manner. ![Animating the above example][2] The images are drawn using Geogebra 3D. [1]: https://i.sstatic.net/3G9ZP.png [2]: https://i.sstatic.net/qrZvp.gif