This is what is called a Fudge dice for the FATE RPG system. The game mechanics revolve around rolling 4 fudge dice to determine if an action was successful. I recently obtained Diaspora, a tabletop RPG that uses FATE and I created this dice (and the d12 version which you can find here http://www.thingiverse.com/thing:870967) in honor of the game. As always, use an X-acto knife, razor blade or a dremel to take off the 'first layer squish' on the bottom of the part where the heat from the bed has melted the plastic slightly (and often printers have a built-in setting that makes the first layer 200% thick). When the bottom layer is slightly wider than the upper layers, it makes the dice not roll as evenly.