Buy a white skirt at a thrift store and doodle it. Wow this is very cool, all done with Fabric paint. Reminds me of the "Yellow Submarine" & "Sgt. Pepper". As I've never had a chance to work with Sharpie pens I'm not sure if they can be used but I think there are ones specially for use on clothing. Check it out. What a great piece ;)
Freezer paper stencils. Use sharpies or fabric markers to scribble in the design instead of fabric paint. No waiting for paint to dry, so good idea for a Brownie meeting, since they can take them home right away.