Hexagonal-enneagonal duoprism

The hexagonal-enneagonal duoprism or hendip, also known as the 6-9 duoprism, is a uniform duoprism that consists of 6 enneagonal prisms and 9 hexagonal prisms, with two of each joining at each vertex.

This polychoron can be subsymmetrically faceted into a digonal-triangular triswirlprism, although it cannot be made uniform.

Vertex coordinates
The coordinates of a hexagonal-enneagonal duoprism, centered at the origin and with edge length 2sin(π/9), are given by: where j = 2, 4, 8.
 * $$\left(±2\sin\frac\pi9,0,1,0\right),$$
 * $$\left(±2\sin\frac\pi9,0,\cos\left(\frac{j\pi}9\right),±\sin\left(\frac{j\pi}9\right)\right),$$
 * $$\left(±2\sin\frac\pi9,0,-\frac12,±\frac{\sqrt3}2\right),$$
 * $$\left(±\sin\frac\pi9,±\sqrt3\sin\frac\pi9,1,0\right),$$
 * $$\left(±\sin\frac\pi9,±\sqrt3\sin\frac\pi9,\cos\left(\frac{j\pi}9\right),±\sin\left(\frac{j\pi}9\right)\right),$$
 * $$\left(±\sin\frac\pi9,±\sqrt3\sin\frac\pi9,-\frac12,±\frac{\sqrt3}2\right),$$

Representations
A hexagonal-enneagonal duoprism has the following Coxeter diagrams:
 * x6o x9o (full symmetry)
 * x3x x9o (hexagons as ditrigons)