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 particular regular constant-torsion polygon has 30 vertices and edges. All angles between adjacent edges are 131.38 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.