I found a method to decently coat a large model with brushes. Of course it doesn't compare with an airbrush job, but it will have to do. It goes a little something like this:
- cover a large surface with color by using a large brush and thinned-out paints.
- repeat the process until the color of the coat is very close to the one in the bottle.
- drybrush the area to cover spots that show irregularities in the paint ;)