Do Your Head In

[Albacore]

I was on the phone the other night taking down a request from client, who was being long winded, and as the conversation went on I started to doodle. I was using both pen and highlighter with clients so I started shading the doodle and it started to move before mu eyes.
What I have found doing this it is the colour combo that makes the illusion it is not really the shape. Try it your self by setting out a centre of rotation you can quickly copy with "ctrl + right Click" with just simple shapes and then getting the colour combo right. Maybe this should be posted in the challenge thread.