https://motherboard.vice.com/en_us/article/9kvwmd/this-3d-printed-clock-runs-on-marbles-and-watching-it-is-soothing-me

There are so many ways to know what time it is. You can wear a watch, check your phone, stare at the sun, or ask a stranger. Time rules us and, sometimes, it crystalizes. Our obsession with time has led to an obsession with clocks and some of those clocks, like Görkem Bozkurt’s 3D printed marble masterpiece, are badass.

Bozkurt is a student at Bilkent University in Turkey where he studies physics. His 3D printed marble clock is based on a design from the 1970s that uses marbles on three different rails to both track time and give a readout. A large system of cogs moves marbles from the bottom rail to the top where they cascade and fill the rails. Add up the different numbers and you’ve got the time. The first two rails count the minutes and the bottom rail counts the hours. At 12:59, marbles fill all the rails and when the clock strikes one, they tumble down and start all over again.