quixote - I think of logic as the procees of imagining formulas. So far we've mentioned: Pyramid Stacking, Ockham's Python, Die Replication, and Pole/Compass Extremities Division. FireHorse - The 12 sided should'nt take too long, it will be much like D8 and D10. D20, and any other suggestions..., are going to take a little longer though. I think the way to do it will be to divide the 180 of lontitude by 4, and the place a light every 72 degrees. Thanks for adressing quixotes question of Logic. I think useablility is a matter of mathmatics! Though I do'nt understand Ockhams Math, I'd consider the rest of the theories presented in this post as worth having at. And would like to hear from anyone who has any other formulae. = )