Here's something interesting. It's the original press release the D5's inventor, Louis Zocchi, sent out for the D5!
"Gamescience News Release - July 2003
New 5 Sided Die Used For Alzheimers Research
Louis Zocchi, President of Gamescience Inc., invented a true 5 sided die, which rolls each of its faces 20% of the time. To assure that the shape would perform as designed, Zocchi made 10 prototypes, each of which was 1mm thicker than the next.
The dice were sent off for testing in a machine created by Dr. Dan Murray in Canada. After each die had been given more than 10,000 rolls, Dr. Murray informed Zocchi that the ideal shape had to be 13.85mm thick. Dr. Murray had plotted the performance changes as one milimeter of thickness was added to each succeeding die, and predicted that a die which was 13.85mm thick would provide ideal performance.
Veterans Administration Medical Center Research Assistant, Ann Charles, phoned Zocchi to confirm that the dice were impartial and available to assist her with the Alzheimers research project [Forget Me Not Research Study: Dementia Project], on which she was working.
She also ordered two 7 sided dice for the same project. These dice are not available in most hobby shops, because distributors feel that customers have no interest in the 100, 24, 16, 7 and 5 sided dice available only from Gamescience."