[Math] Mark the sides of a dice

[bhargava]

When you roll two six-sided fair dice, the total number of dots displayed can be anything from 2 to 12. However, some sums are more likely than others. Now suppose you have two six-sided fair dice, with no dots on any of the faces (they are blank). Armed with only a marker pen and your puzzle-solving prowess, how can you draw dots on the dice so that each possible sum will appear with equal probability?

Solutions other than the trivial solution of putting the same number of dots on all sides.