The hardest part of the design was generating the graphical image. I chose a 7-segment LED style because I figured it would be the easiest to generate. Of course, a plain 7-segment representation, where each segment was a rectangle, proved to be too simple, so I had to make the segments with a nice diagonal corner so they'd fit together nicely. Sometimes, I just have too much time on my hands.
Figure 1. The simulated 7-segment digits.