by Vinsssounet
Well first everything was spray primed white. Though several people said the paint would stick without primer, I wouldn't take a chance !I did the base colors with a paint gun. 2 layers, 3 sometimes, depending on the colors. At this point the cogs are a unique, regular color.
Note that the paintgun is not a necessity, I actually ran out of propellant and did the yellow wheel with a (big) brush.
This part isn't part of your question but I then redid some white spray primer around the wheels, so there would be little gradients on the extremitys.
I then just repainted white the small worker-circles, with a brush. With a diluted white, (not TOO diluted, just milky) the paint will quite naturally follow the inner circle and look regular. Just turn the wheel while painting so you always follow the circle with the same movement.
Once they were all white (ugly white, hardly opaque, just enough so I could paint something else above it) I redid it with whatever color I wanted. Took 2-3 well-diluted layers.