A restless Japanese scientist came up with the idea to turn bath water into a touchscreen display. They even brought it to life with a projector and a Kinect sensor.
The engineers at Tokyo University of Electrical Communications named their unusual system AquaTop Display. It allows you to use a Kinect controller, LED projector and waterproof speakers to turn the surface of the bathtub water into a touchscreen display for games and entertainment. True, it is also necessary to add a special salt or liquid to the water beforehand, which will color it in a milky white color. This will provide the best contrast.
The unusual display can be operated in several ways - by barely touching the surface of the water or by touching the surface below, in the water. On the improvised display, you can "run" the simplest games or use it to view photos and videos.