# Tri-stable convex body. A D3 dice

This question is inspired by the Gömböc - a convex three-dimensional homogeneous body that when resting on a flat surface has just one stable point of equilibrium:

https://en.wikipedia.org/wiki/Gömböc

I expect that this shape is not described in the literature, as the creators are selling them very expensively!? I have not been able to find any articles about the shape, or the math behind it. It does not even seem like any independent party has confirmed the shapes properties!

What I am looking for is a shape with three stable points, that can be used as a dice. I am not happy with the symmetry of the conventional extruded triangle with rounded ends like this:

-so I designed my own naive thing(green is flat, gray is curved):

It is a cube, where three of the surfaces is cut away with a curve. I already knew that it would not work, but I tried.

The problem as can be seen is that the shape can lie on the curve, so the shape still has six equilibrium points like the cube.

My question: I am seeking a mathematical description of a 3D shape that can be used as a dice with three sides. I would like if it was:

• convex
• homogeneous
• has three stable points of equilibrium on a flat surface
• has a high degree of symmetry.

The 'high degree of symmetry' requirement is not well defined, but I hope that someone can help with that.

Does such a shape exist? How would one describe and classify such shapes?

• Kids today want everything to look like a darn UFO. In my day, we rolled an ordinary 6-sided die and modded the result by 3. And we liked it that way. Aug 10, 2019 at 3:46