Dial any spray paint color on demand with Spectrum

Is there any artist that wouldn’t love to have a magic spray paint can that changes to any desired color on demand? Imagine the murals you could paint! Well, Sandesh Manik is a genius who actually achieved that with Spectrum.

Spectrum is an on-demand spray paint-mixing machine worn like a backpack. Just adjust the ratios of the four base colors (white, red, yellow, and blue) using dials on the control panel, then press the button on the handheld sprayer to start painting. The system thoroughly mixes all of the colors by pulsing the output from each can in bursts lasting no more than 250ms, ensuring that the output is consistent.

The exact pulse timing depends on the color mix. A pink, for example, might need one part red to four parts white. In that case, it would pulse red for 50ms and white for 200ms, then continue repeating that pattern until the user releases the button.

It does the mixing by opening and closing custom valves, designed and made by Manik, that pinch hoses to stop flow. An Arduino Nano controls the valves, performing the pulsing sequence when it detects force on a pressure sensor in the sprayer unit. It does so according to the values it reads from potentiometer dials and displays the information on an OLED screen.

This is a very clever and surprisingly affordable system. Manik says the entire build costs less than $150, which is a bargain for chromatic versatility it provides.