I'm sure leopard print would turn out fantastic!
I use a few kinds of substances: body paints, body crayons and casual make-up kits. I also like writing some quotes and making detailed graphics using normal pens and colourful marker pens, however I don't do it too often as it may irritate the skin.
What I enjoy the most is making a stylized make-up, for example the one done in Mexico for the Day of the Dead (it's my favourite one to do ^^). I tend to use body crayons besides the usual kits for make up for that.
If you had a slightly wider choice of colours, just as you said, you'd be able to mix them to get new ones. It's so fun (at least for me!)
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So do you do 'tattoos'? What substances do you actually use - are they body paints or something different?