Stonehenge is a time robot which manually replacing time cards one by one. I’m not sure it’s efective or not, but it seems Stonehenge would move restlessly for every minutes to change the card because it moves rather slow! 
“The name ‘Stonehenge’ comes from the fact that the cards are arranged in a semi-circle around the arm so that the software can easily keep track of where they are.”
– OhGizmo!
Here is the real demonstration of Stonehenge robot clock:
It’s cool, but pretty slow, right?
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