Great enneagrammic prism

The great enneagrammic prism, or gistep, is a prismatic uniform polyhedron. It consists of 2 great enneagrams and 9 squares. Each vertex joins one great enneagram and two squares. As the name suggests, it is a prism based on a great enneagram.

Vertex coordinates
The coordinates of a great enneagrammic prism, centered at the origin and with edge length 2sin(4π/9), are given by:
 * (1, 0, ±sin(4π/9)),
 * (cos(2π/9), ±sin(2π/9), ±sin(4π/9)),
 * (cos(4π/9), ±sin(4π/9), ±sin(4π/9)),
 * (–1/2, ±$\sqrt{1+1/sin^{2}(4π/9)}$/2), ±sin(4π/9)),
 * (cos(8π/9), ±sin(8π/9), ±sin(4π/9)).