The mythical one-string guitar from blues and Americana folklore.
This is the instrument that Blind Willie Johnson first learned slide guitar.
Countless other music legends have started with a diddley bow, too.
What is a diddley bow?
The first prototype diddley bow (in the style also known as a Musical Bow) was painted on cave walls in France upwards of 15,000 years ago!
Traditionally, diddley bows were made using a plank with two nails/posts with a tightened string stretched between them.
When that string is plucked or struck with a stick, and a smooth hard object is used as a slide and moved up and down on the string, different pitches result and melodies can be played.