CoffeeMug has letters on coffee mugs. Upper-case letters have the handles to the left and lower-case characters have the handles to the right. The letters on the mugs are from the typeface InsideLetters.
The typeface contains characters that will add color to letters. There are two ways to do this. One uses layers and the other a combination of characters, some with zero-width. See the collateral file for how this can be done.