Thanks for all the advise. I should have been clearer in the reason for my question. I was actually talking about touching up playfields, and in particular, touching up small areas where you'd be lucky to use a ml or two of paint. That's why I need to mix and match paint and try to fudge the finish as well. Not worth buying 500ml for some of the touch ups I need to do, and I need probably 6 colours to match, which could equate to 18 colours or so for mixing.