Mason Green's Small Supersemicupola

This is Mason Green's small supersemicupola. Despite the fact that this polyhedron 'only' has D₇C₇ symmetry I think this is a surprisingly special polyhedron and it is a great find by Mason Green. The polyhedron has a {7/2} base with regular heptagons on the sides. There are seven of these sides and each side shares an edge with two of the other sides. The dihedral angle is such that a equilateral triangle fits in between on both sides of the edge. This gave rise to a little investigations into what I referred to as roof top polyhedra.

A special property of this polyhedron is that it has a membrane: the heptagon inside the {7/2} is seen from both sides. Since I use paper that only has a colour on one side, it meant that I had to cut and paste both sides. This model was built in July 2025 and edge length is 3.6 cm.

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Last Updated

2026-03-17