a parametric rigged dice. you can choose the face that will most likely show up, the amount of crookery to put inside, and about all other parameters you may think about.
edit
I finally had a chance to have one of these printed before I received my printer, and i learnt a couple thinks :
*The round corners (value was set to 0.8) are pretty challenging to print, too much overhang. Try higher values

• 0.1 is too small. Try dot depths of at least 0.5mm
  *infill must be set to 100, at 20% there is not enough weight to obtain an observable shift in the odds of getting the rigged face up.