Behold the "Circle Guitar", an invention of Anthony Dickens, which has a motor-driven disk that spins and strums the strings. You can place pick-pegs in the disk to represent different strumming patterns, so it's sort of like a MIDI sequencer for strumming — the guitar self-strums the patterns with machined precision, at up to 250 picks-per-second.
The upshot is that you can play stuff that sounds like sequenced synthesizer — except with the particular percussive tones that you get from an actually-plucked string.
The Circle Guitar generates a time code which other instruments can follow, or it can be synchronized with the clock of a digital audio workstation over USB, expanding creative options by, for example, phasing the disc rotation in front of or behind the beat, or engaging a swing motion where the spin slows for a time before speeding up again.
The player's fretting hand is used pretty much like on a standard guitar, forming chord shapes or changing pitch at the frets on the rosewood fingerboard. Individual strings can't be singled out for attention during the spin, all of the strings are struck by the guitar picks attached to the spinning disc, but the player can mute strings at the body or neck if desired.
"The smallest movement from your fingers can create big tonal changes, especially when rhythmically moving fingers back and forth over a few strings to allow them to intermittently play before muting them again," Dickens told us. "Moving your fingers around the strings produces crazy harmonics – moving from tonal to atonal sounds."
Here's Ed O'Brien from Radiohead playing it, and discussing its creative potential ….