We've tested some strange things over the years, but this has to take the biscuit, or indeed the tin can.
The diddley bow was created in the American South - and before that in Africa - by nailing a piece of wire to the side of a shack (or something more portable) and creating a vocal-like wailing tune by sliding a piece of metal or glass up and down it: a one- string slide 'guitar'.
Our sample is more sophisticated, but not much - like a one-string lap-steel with a bolt as the nut and a slightly flattened tin can as the bridge/ resonator. A rather over-spec'd Gibson-style humbucker picks up the sound, and we even get a volume control.
All of this, along with a transparent stick-on fret guide, is mounted on a tapered piece of two-and-a-half by four-inch pine.
We tuned the thick unwound string to G, picked up a slide (a kitchen knife worked well!) and made a right ol' bluesy racket that modern slidesmiths such as Jack White or Seasick Steve would be proud of.
Fans of African and Asian music will easily find a use for it, too. It has a honky resonance, very different from even the cheapest lap-steel, and plugged in with some gain it also has a tendency to self-oscillate like a kind of lo-fi Fernandes Sustainer or other-worldly theremin, but in a good way.