Shadowplay strips the clock back to its basic elements, with an empty clock face bathed in light from the LEDs embedded in its plywood frame. There are no numbers, and no hands, at least until someone touches the clock face, at which point the time is picked out in two shadowy streaks which extend past the edge of the clock.
This happens because touching the clock face turns off all but three of the LED lights around the edge, thus casting the shadow of the time at that moment. The lights are controlled by an Arduino microcomputer, which tracks the time and determines which LEDs need to be switched off to cast the correct shadows.
Shadowplay, as shown in the video below, is a piece by design studio Breaded Escalope, and was displayed at the Ganz Neue Gallerie in Vienna during the city's design week held between September 25th and October 4th.
The clock is currently just a prototype, with any future plans to sell it still unclear. However, anyone with an Arduino, some programming skills, and basic woodworking skills could probably create something very similar over a weekend.
Source: Breaded Escalope via Dezeen