If you're good with a dremel/rotary tool, you can go to your local hardware store and buy various couplers for PVC piping, just the plain white stuff you use for irrigation. Draw a design on there with a pencil or pen, dremel them down, sand with a fine grit paper if you want them smooth, paint and BAM, dread rings. I'd suggest 1/2, 3/4 and 1 inch couplers.