You can buy the empty 'can' unit and put whatever liquid paint you want to. However, why limit yourself if you're going custom color? I can see using Krylon, over-the-counter, etc. (which can be done quite well if you know what you're doing), but think it'd be better to either use a real spray gun, or even an airbrush could work well, if concerned about space, small compressor, etc...Use an inline separator-dryer on the line, of course.