This is an aid for rolling dice, in place of throwing or tossing them. When playing a game with young children it may be easier than finding the dice after erratic rolls. At least the dice will be confined to a smaller area.
For people with manipulation issues it may be easier and more consistent than the throw-release motion.
Print and clean up the exterior of the part.
Drop a pair of 16 mm dice into the top and note how they tumble to create random numbers.
This is for a pair of dice that are 16 mm cubes (roughly 5/8 inch). If you have smaller or larger dice and this does not tumble them or they wedge, simply scale it up or down appropriately.
There is the start of a hole in the bottom, which can be used to attach it to a lipped base for stability.