Equiprojective polyhedra
In mathematics, a convex polyhedron is defined to be -equiprojective if every orthogonal projection of the polygon onto a plane, in a direction not parallel to a face of the polyhedron, forms a -gon. For example, a cube is 6-equiprojective: every projection not parallel to a face forms a hexagon, More generally, every prism over a convex is -equiprojective. Zonohedra are also equiprojective. Hasan and his colleagues later found more equiprojective polyhedra by truncating equally the tetrahedron and three other Johnson solids.
shows there is an time algorithm to determine whether a given polyhedron is equiprojective.