(Nope, it’s not a glimpse of an alternate reality where LEDs never came to be.) The “Stonehenge” clock-bot is more art than appliance – it uses a single robotic arm with a set of numbered cards to convey the time –
Stonehenge uses a CrustCrawler Smart Arm and a Parallax Propeller chip to display the current time. All the digits needed to display the time are located on cards positioned in a semi-circle around the left and right sides of the arm. The time itself is displayed in front of the arm. This gives the clock a “Stonehenge” like appearance. There are a total of 14 cards. Each card has two digits with one on each side. The software planner determines which card and which side is needed to display the time and then sends the necessary movement commands to the arm.