Square ditetragoltriate

The square ditetragoltriate or squiddet, also known as the 8-3 quadruple step prism or digonal truncatoprismantiprismoid, is a convex isogonal polychoron and the second member of the ditetragoltriate family. It consists of 8 square prisms and 16 rectangular trapezoprisms. 2 square prisms and 4 rectangular trapezoprisms join at each vertex. However, it cannot be made uniform. It is the first in an infinite family of isogonal square prismatic swirlchora.

This polychoron can be alternated into a digonal double antiprismoid, which is also nonuniform.

It can be obtained as the convex hull of 2 similarly oriented semi-uniform square duoprisms, one with a larger xy square and the other with a larger zw square.

It can also be constructed as a subsymmetrical faceting of the truncated hexadecachoron.

Using the ratio method, the lowest possible ratio between the longest and shortest edges is 1:2. This value is also the ratio between the two sides of the two semi-uniform duoprisms.

Vertex coordinates
The vertices of a square ditetragoltriate, assuming that the trapezoids have three equal edges of length 1, centered at the origin, are given by:
 * $$\left(±\frac12,\,±\frac12,\,±1,\,±1\right),$$
 * $$\left(±1,\,±1,\,±\frac12,\,±\frac12\right).$$