Some of my favourite products come about when those in non-technical professions have an idea and embark on a journey combining technology with their own love. This is a perfect example of that. Musician Pete Roe found himself needing a bass player while on tour to accompany him. Lacking the van space he had to get creative. His idea was to hijack two of his guitar strings and have them output different sounds, effectively turning his guitar into two.
The concept is similar to the main guitar pickup on electric guitars. A pickup is a coil of wires which are placed just below the metal strings. When a string is plucked the magnetic field produced by the coil is disturbed and fluctuates the current running through it. This current is then translated into sound.
Submarine is just a smaller version of that and is stuck under two of the strings using a Gecko pad. A switch allows the player to manipulate either or both of the strings and the sound is incredible.
Pete has a working version and his crowdfunding campaign will launch soon to raise funds to produce it.