I love finding antique display technology on eBay and a few days ago I came across a dozen old edge lit displays, also known as lightguide displays. Basically, a piece of plastic is bent to allow light to enter at the rear of the device. This plastic guides the light to the front where small holes are dilled to form numbers of symbols. Each digit or symbol has a corresponding lightguide and incandescent bulb. If one were so inclined, you could also swap these bulbs out with a nice LED and come up with a display that offered more colors and was easier to drive using contemporary circuitry.
I created a quick video showing how the device works – enjoy!
Video and photos after the break: