In a regular constant-torsion polygon,
all edges have the same length,
all angles between adjacent edges are the same,
and all torsion angles (dihedral angles between adjacent angle-spanning planes) are the same in absolute value.
This regular constant-torsion polygon is a variant of Regular Constant-torsion Polygon (++--)^4,
but with a rotated beam, to avoid flat miter joints.
It has 16 vertices and edges.
All angles between adjacent edges are 130.06 degrees,
and all torsion angles are 90 degrees (in absolute value).
The signs of the torsion angles are given in the title.
The original is constructed from square wooden beams.
Designed by Koos Verhoeff.