A Digital Clock Uses 60 Water Bottles Instead of LEDs

This digital clock forms four digits using blue-dyed water in small bottles instead of LEDs. Each digit has a 3-by-5 grid of fifteen bottles, for sixty in total. An initial design with a shared pump and valves suffered from leaks and air in the lines. The final mechanism uses a tiny pump for each bottle, then tips the bottles to empty them when the display needs refreshing.