Bob Murrell combined his knowledge of guitars and electronics to invent the GuitOrgan. It is a hybrid electric guitar and organ. The strings and frets are wired into a circuit such that the organ notes play when the string is fretted. The organ section in a Guitorgan is a 6-note polyphonic circuit, which allows full guitar chords to be played. There is also a button on the Guitorgan's neck that allows the use of open chords. The instrument also has conventional guitar pickups and the organ notes can be played alone or simultaneously with the guitar. The expert "Guitorganist" can use the Guitorgan's expression pedal to bring the organ in and out of the musical foreground, while playing the guitar at the same time,as if there were two musicians playing.

Murrell was converting existing guitars into GuitOrgans at home from the late 1960s. Murrell demonstrated his GuitOrgan prototype at the 1967 Chicago NAMM show. In 1968, he had a production run of instruments based on semi-hollow body guitars imported from Japan. The B-300 and M-340 are the most common examples from this run. Murrell's company which started out as Murrell Electronics was eventually renamed Musiconics International (MCI). The GuitOrgan lived on until the 1980s, as Murrell continued to upgrade his designs, with analog synth interfaces and even MIDI. An estimated 3000 Guitorgans were made between 1967 to 1984. Bill Murrell continued to build Guitorgans as custom orders after 1984.