Octagrammic retroprismatic prism

The octagrammic retroprismatic prism or storpip is a prismatic uniform polychoron that consists of 2 octagrammic retroprisms, 2 octagrammic prisms, and 16 triangular prisms. Each vertex joins 1 octagrammic retroprism, 1 octagrammic prism, and 3 triangular prisms. As the name suggests, it is a prism based on an octagrammic retroprism. Being a prism based on an orbiform polytope, it is also a segmentochoron.

Vertex coordinates
The vertices of an octagrammic retroprismatic prism, centered at the origin and with edge length 1, are given by: An octagrammic retroprism of edge length 1 has vertex coordinates given by: where $$H=\sqrt{\frac{-2+2\sqrt2-\sqrt{20-14\sqrt2}}8}$$
 * $$\left(±\frac12,\,±\frac{\sqrt2-1}2,\,H,\,±\frac12\right),$$
 * $$\left(±\frac{\sqrt2-1}2,\,±\frac12,\,H,\,±\frac12\right),$$
 * $$\left(0,\,±\sqrt{\frac{2-\sqrt2}2},\,-H,\,±\frac12\right),$$
 * $$\left(±\sqrt{\frac{2-\sqrt2}2},\,0,\,-H,\,±\frac12\right),$$
 * $$\left(±\frac{\sqrt{2-\sqrt2}}2,\,±\frac{\sqrt{2-\sqrt2}}2,\,-H,\,±\frac12\right),$$

Representations
An octagrammic retroprismatic prism has the following Coxeter diagrams:
 * x2s2s16/5o (full symmetry)
 * x2s2s8/5s
 * xx xo8/5ox&#x (octagrammic prism atop gyrated octagrammic prism)