Make a stencil. Draw or print the design on a piece of very stiff paper, and cut it out with a craft knife. Then wrap it around the chuck tightly and secure it with tape. Cover the rest of the wood and chain/cord with tape, and spraypaint the stenciled design into the wood. That's more or less how they detail cars. Then remove the stencil and tape, and coat the whole thing in varnish so the design won't rub off. Make sure beforehand that your paint is intended for the surface you're using. If you do it right, you should be able to use the same stencil several times.
EDIT: I forgot to mention, if there's a part of the design separate from the stencil, you'll need to cut it out of tape and apply it to the wood. It would probably be easier to apply the tape directly onto the wood, and then carefully cut out the design from there.
