Spectrum: DIY Spray Paint Mixer Creates Hundreds of Custom Colors from Four Base Cans
One System, Hundreds of Colors, Endless Possibilities
A former Google X hardware engineer has spent seven years developing Spectrum, a DIY spray paint system that mixes custom colors in real-time from just four base cans. The $150 system uses pulse-width modulation — a technique borrowed from LED brightness control — to blend red, yellow, blue, and white paint into hundreds of distinct hues, all from a single spray head.
The Problem
Professional spray paint artists must carry dozens to hundreds of separate cans to every job site. Unlike traditional paint, spray paint can't be blended once aerosolized — the droplets can't mix in mid-air. This means every desired color requires its own can.
The Solution: Pulse-Width Modulation for Paint
The breakthrough came from an unlikely source. Sandesh Manik, the creator, borrowed a trick familiar to anyone who has controlled LED brightness with a microcontroller: pulse-width modulation (PWM).
Instead of trying to mix pressurized paint from multiple cans simultaneously (which failed due to pressure differences causing backflow), the system opens valves sequentially in rapid cycles:
- Want clementine orange? Yellow valve opens for a period, then red for twice as long
- The cycle repeats rapidly (pulses as short as 30 milliseconds)
- Natural turbulence in the flow provides sufficient mixing
- Result: instantly blended colors from the spray head
A Custom Valve to Solve Clogging
Off-the-shelf solenoid valves constantly clogged with paint. Manik invented a high-speed rotary pinch valve:
- Uses a stepper motor to constrict a flexible tube
- Spring-loaded for normally-closed operation
- Prevents backpressure and leakage
- Cycles in as little as 30 milliseconds
- Keeps paint out of the mechanism entirely
Technical Specifications
| Feature | Specification |
|---|---|
| Base colors | Red, Yellow, Blue, White |
| Pulse duration range | 30-250 ms (8 values) |
| Distinct colors | Hundreds (under 4,096 theoretical) |
| Tube diameter | 1 mm |
| Controller | Arduino Nano |
| Total cost | Under $150 |
The Gradient Feature
A force sensor on the trigger button allows blending between two programmed colors based on finger pressure — creating smooth gradients without switching settings.
Open Source
Manik has published all project files, technical papers on the valve design and mixing methodology on TechRxiv, and step-by-step instructions for non-technical users to build their own system.
The Journey
Working on and off for about seven years, Manik went through four major prototypes with "spectacular failures along the way of the sort that only pressurized paint can provide." Since posting a video, he's received positive responses from spray paint artists worldwide.
"I look forward to seeing what creations artists out in the wild make!"