Nendo created not one, but two unique options.
Rassen (above) and is a round chopstick created from a single piece of milled wood. This twisty utensil comes as a single unit that can be separated into two for eating, and then rejoined when not in use. The second is called Kamiai (below) and it's also interlocking, but in quite a different way that takes advantage of its square shape. Each piece has a magnet embedded into the wide end, which allows the two pieces to snap together into one form, but they're placed toward the outside of each chopstick, so that they don't accidentally do so when they're actually being used to eat.
(Via The Fox Is Black)