Baling wire is useful in rigging tri-string wands. It is both strong and malleable and rust-resistant. It can be used to create an attachment point on a tri-string wand by drilling a hole through the wand and threading some baling wire through the hole. Make a loop with the baling wire to which a wand lead can be attached and then wrap the baling wire around the pole a few times. The wraps and hole can be covered with heatshrink tubing.
Baling wire is available at shops that stock farming materials and some hardware/home improvement stores (such as Orchard Supply Hardware) but many such stores do not carry it.