>>11382254I just have one of these filled with tap water. When I'm done with a colour I'll blast it into the cup over a jar or something till the colour runs clear.
Then blackflush some tamiya thinner, dump it out, wipe the cup with a paper towel. Then just spray a bit more thinner through the airbrush till it comes out clean. Repeat as necessary.
Then I leave a bit of thinner in the airbrush to sit to make sure there's no stubborn bits till I need to use it.