This was a 'what-if' moment. I did not use colours or make-up. I had to keep my restless kids engaged for a while. I promised them some fun with colours in their images. I was going to use a flash gel to paint them purple. In a moment of inspiration, I tried reflecting light from flash using a CD instead. What if I could get rainbow colours instead of just one colour! The CD dispersed white light into its component colours, just like how a prism would. And we ended up with light painted kids!