Concave Dodecahedron

Like the regular dodecahedron, this model has 12 pentagonal faces, but the pentagons are concave and the resulting polyhedron is concave. When the double dodecahedron dissection (see the description of my other class, "Triple D") is folded up into a pentagonal dodecahedron, it is solid all the way to its center, but when it is folded up into a rhombic dodecahedron, there is a void in its interior. The figure is the shape of that void.