Maker Strange Inventions has built a water-based digital clock in which 60 small bottles act as individual pixels, collectively forming numerals to display the time. The bottles, sourced at 10 cents each, brought the total project cost to approximately $580. Each bottle is filled or emptied with dyed water to switch its pixel state on or off, with the display controlled by a microcontroller managing the pump and valve system.
The build went through several major design revisions before reaching a working state. An initial approach used a single peristaltic pump paired with solenoid valves to route water to individual bottles, but persistent leakage from splitters and unequal flow resistance between bottle paths made reliable operation impossible. A follow-up concept using small motor-driven membrane pumps connected in a loop was also explored and ultimately abandoned. The final solution routes water with a membrane pump and empties each bottle by flipping it using a servo, with the tube routed through the servo axis to avoid interference. A custom bridge structure was built over the tubing to mount the servos.
Assembly of the full clock took roughly three months and involved repeated mechanical troubleshooting, including friction issues with rotating bottle mounts that were resolved by sanding and lubricating the sliding surfaces. Power supply inadequacy caused uneven bottle filling until a higher-capacity unit was substituted. After replacing faulty pumps and tuning the mechanics, the clock was demonstrated fully operational.
