Enneagonal-tetrahedral duoprism

The enneagonal-tetrahedral duoprism or etet is a convex uniform duoprism that consists of 9 tetrahedral prisms and 4 triangular-enneagonal duoprisms. Each vertex joins 2 tetrahedral prisms and 3 triangular-enneagonal duoprisms.

Vertex coordinates
The vertices of an enneagonal-tetrahedral duoprism of edge length 2sin(π/9) are given by all even sign changes of the last three coordinates of: where j = 2, 4, 8.
 * $$\left(0,\,1,\,\frac{\sqrt2\sin\frac\pi9}{2},\,\frac{\sqrt2\sin\frac\pi9}{2},\,\frac{\sqrt2\sin\frac\pi9}{2}\right),$$
 * $$\left(\cos\left(\frac{j\pi}{9}\right),\,±\sin\left(\frac{j\pi}{9}\right),\,\frac{\sqrt2\sin\frac\pi9}{2},\,\frac{\sqrt2\sin\frac\pi9}{2},\,\frac{\sqrt2\sin\frac\pi9}{2}\right),$$
 * $$\left(-\frac12,\,±\frac{\sqrt3}{2},\,\frac{\sqrt2\sin\frac\pi9}{2},\,\frac{\sqrt2\sin\frac\pi9}{2},\,\frac{\sqrt2\sin\frac\pi9}{2}\right),$$