This is fairly old (1999) but very cool — Daniel Rozin’s Wooden Mirror uses an array of wood chips mounted on tiny servo motors which position themselves to reflect light in something resembling grayscale (woodscale?) in response to a processed image coming in from a tiny camera in the middle of the array. The result is a panel of wood chips that reflects the appearance and motion of the person standing in front of it.
This QuickTime movie is probably the best way to appreciate (catch the second half for close-ups). Can’t recall having seen digital technology used to create such a totally analog experience before. Runs on an old Mac 8600 AV, software written in a combination of C and Macromedia Director, of all things.