Conventional dice are open to the accusation that they are unfair -due to the inbuilt moment-of-inertia asymmetries of different faces (eg six recessed dots don’t rotate in exactly the same way as two). This new die attempts to avoid that problem.
The design consists of a dished cube set within an outer,transparent cube. The inner is fixed within the outer by thin arms at the 8 corners.
The space between inner and outer contains 42 identical spheres.
Each of the dishes is made to accommodate up to six of them when the die is tossed (there is a gap between inner and outer which is just a little more than one sphere-diameter deep, so that spheres can only form a monolayer).
The remaining spheres crash to the bottom of the die each time.