All of the dice in this set are geometrically defined by fitting inside 25mm diameter spheres. The container is an array of 7 spheres that are all 25mm diameter with a little clearance so they fit the dice perfectly.
The blue dice in the picture are made with FormLabs tough resin.
The case was originally designed for 9.5mm x 19mm magnets but can be redesigned to fit many others, please let me know if you need it modified.
The author hasn't provided the model origin yet.