Heptagrammic-great enneagrammic duoprism

The heptagrammic-great enneagrammic duoprism or shegstedip, also known as the 7/2-9/4 duoprism, is a uniform duoprism that consists of 9 heptagrammic prisms and 7 great enneagrammic prisms, with 2 of each at each vertex.

The name can also refer to the great heptagrammic-great enneagrammic duoprism.

Vertex coordinates
The coordinates of a heptagrammic-great enneagrammic duoprism, centered at the origin and with edge length 4sin(2π/7)sin(4π/9), are given by: where j = 2, 4, 6 and k = 2, 4, 8.
 * $$\left(2\sin\frac{4\pi}{9},\,0,\,2\sin\frac{2\pi}{7},\,0\right),$$
 * $$\left(2\sin\frac{4\pi}{9},\,0,\,2\sin\frac{2\pi}{7}\cos\left(\frac{k\pi}{9}\right),\,±2\sin\frac{2\pi}{7}\sin\left(\frac{k\pi}{9}\right)\right),$$
 * $$\left(2\sin\frac{4\pi}{9},\,0,\,-\sin\frac{2\pi}{7},\,±\sqrt3\sin\frac{2\pi}{7}\right),$$
 * $$\left(2\sin\frac{4\pi}{9}\cos\left(\frac{j\pi}{7}\right),\,±2\sin\frac{4\pi}{9}\sin\left(\frac{j\pi}{7}\right),\,2\sin\frac{2\pi}{7},\,0\right),$$
 * $$\left(2\sin\frac{4\pi}{9}\cos\left(\frac{j\pi}{7}\right),\,±2\sin\frac{4\pi}{9}\sin\left(\frac{j\pi}{7}\right),\,2\sin\frac{2\pi}{7}\cos\left(\frac{k\pi}{9}\right),\,±2\sin\frac{2\pi}{7}\sin\left(\frac{k\pi}{9}\right)\right),$$
 * $$\left(2\sin\frac{4\pi}{9}\cos\left(\frac{j\pi}{7}\right),\,±2\sin\frac{4\pi}{9}\sin\left(\frac{j\pi}{7}\right),\,-\sin\frac{2\pi}{7},\,±\sqrt3\sin\frac{2\pi}{7}\right),$$