So it was more of a physical problem rather than a mathematical one [1]:

> Harshbarger says he and his colleagues always knew the dice were mathematically possible.

> The mystery was whether that mathematical solution could be translated into the physical geometry of a die — something that could actually be manufactured and rolled.

> “I knew there was a solution with something crazy like 1,440 sides for each die,” he said. “That's not makeable.”

[1] https://www.cbc.ca/radio/asithappens/dice-mystery-board-game...