Below is a wheel with simple fourth intervals followed by its upper extension equivalent following the slash.
The core of the NANDI method is based on visualizing the fretboard as fourths. Chords built by stacking fourths are called quartal voicings. Here are 3 examples of major, minor and dominant chords built on fourths.
You can build quartal voicings from every note of a major scale by stacking fourths. Seen below is a harmonized C major scale using quartal voicing.
Here are the chords: From the root -maj7 (11) from the second, third, sixth and seventh scale degrees- min7 (11), from the fourth a major7#11, from the fifth a dom7 (11).
