I wouldn’t go for pictures or patterns or symbols or icons, that stuff dates. If you’re going to do it do a proper job. do one whole hand yellow the other blue. when you get bored, do a layer of blue on the yellow hand to make it green, then a layer of red on the blue hand to make it purple. Keep going every few years till both hands are black or a muddy brown. Like mixing plasticines. Then start afresh on another body part.