If we were handy enough to build our own sinks, we’d build one exactly like this “The Ripple” faucet, designed by Smith Newnam, which equates relative ball movement to the temperature and amount of water flowing out.
Hot water makes the LED glow red, while cold makes it glow blue, and the two hot and cold channels mix together in the open air to make for your desired temperature. Awesome ? Definitely. Practical ? Not so much.