You can use straight water to dilute Tamiya acrylic paints. you dont have too use thier fancy thinner, witch is almost all alcohol anyway. And why does it take 3 or 4 jars of paint to paint one tank. I usually get atleast 3 paint jobs from on 3/4 once jar of Tamiya paint. I allways airbrush though. I could see using more paint if your use an actuall paint brush, but that still sounds like a lot of paint.