The backboard on a pinball machine sits vertically at the rear and typically displays the score along with some sweet artwork. My design consisted of a box with an acrylic front to show off the scores and back-lit artwork. From the back it looks like this:
I printed the artwork on to translucent plastic, so I could light it up from behind.
A power efficient back-light was built from lots of white LEDs, and installed behind the artwork.
There are also a bunch of 7-segment displays and other LEDs wired up for the game displays.
The finished display looks pretty damn good: