Batik with fabric paint!

If you're repainting your old fabrics anyway, then try making a pattern! There are loads of colours for both hand-dyeing and dying in the washing machine.
To make rings: Measure out the midpoint and pinch it; pull up and let the rest fall down. Tie the string where you want to make rings. Wrapping the string around several times will result in stronger rings. Moisten the fabric and dye according to the instructions on the package.