As discussed on the Isomorphism page, there are various isomorphic patterns, ways of dividing up the twelve notes of the chromatic scale. One of these is the 4-4-4 pattern, found for example in chromatic notation systems with lines spaced three semitones apart (a minor third apart), such as Numbered Notes by Jason MacCoy.
This pattern is also found on the Chromatic Button Accordion, where the buttons are arranged chromatically in rows of three. It is also present in the three-color pattern of Roy Pertchick’s Isomorphic Vibraphone (YouTube video), where it overlays a 6-6 pattern physical layout of the instrument.
The tutorial on Intervals in 6-6 Music Notation Systems explores how notation systems with a 6-6 pitch pattern improves upon the appearance of intervals in traditional notation. The following image expands on that discussion by showing how intervals appear in a 4-4-4 notation system. With the 4-4-4 pitch pattern each interval has three distinct appearances (whereas with a 6-6 pitch pattern each interval has two appearances).