Great heptagrammic prism

The great heptagrammic prism, or giship, is a prismatic uniform polyhedron. It consists of 2 great heptagrams and 7 squares. Each vertex joins one great heptagram and two squares. As the name suggests, it is a prism based on a great heptagram.

Vertex coordinates
The coordinates of a great heptagrammic prism, centered at the origin and with edge length 2sin(3π/7), are given by:
 * (1, 0, ±sin(3π/7)),
 * (cos(2π/7), ±sin(2π/7), ±sin(3π/7)),
 * (cos(4π/7), ±sin(4π/7), ±sin(3π/7)),
 * (cos(6π/7), ±sin(6π/7), ±sin(3π/7)).