This has probably been suggested in the past but, I bought a cheap stamp pad, rinsed the ink out, moistened the pad with water and brushed Vallejo black/grey acrylic onto the pad. The faces of the road wheels from the tank were painted first, and then the edges were rolled across the stamp pad. It only took about ten minutes to do sixteen wheels. The depth of paint on the wheels can be varied by increasing ar decreasing the pressure against the pad or by tilting the wheels.
The paint didn't dry out because the pad was moist and the pad washed out nicely after I finished with it.
I don't know if this would work with enamels or oils.
Craig