Cubes, cuboids, tetrahedron and prisms are examples of polyhedra. When you open out a polyhedron as a net, it shows all the polygons that it is made from. For example here is the net of a cuboid.

A new kind of 3D display could take the form of an acrylic cube with an image inside, which can be erased and rewritten to easily. The new technique can be used to make 2D, 3D and even animated ...