The 0x33.board supports various different isomorphic keyboard layouts based on hexagonal grids. The current layout and the note to start the scale with in the bottom-left corner of the main grid can be set in the settings screen.
For each layout, the diagram below shows (a possible) arrangement of twelve semitones in an octave. The keys highlighted in yellow and purple form a major scale with the yellow keys delineating a single octave.
The Wicki/Hayden Note Layout is an isomorphic note layout conceived and independetly rediscovered in 1896 and 1986 respectively. The intervals between neighbouring keys are 2, 5 and 7 semitones, arranged such that a whole-tone scale lies horizontally along rows. The keys of an octave repeat vertically every second row.
The Jankó keyboard was designed in 1882. Moving along rows to the right keys are 2 semitones apart, whereas the four diagonal intervals are all single semitones.
Keys are duplicated vertically without a change in octave, unlike the Wicki/Hayden layout. As a result this layout only fits two octaves on the keyboard, but is arguably the clearest mapping.
The Harmonic Table note-layout is known since at least the 18th century. The intervals between keys are 3, 4 and 7 semitones.
In this layout the major and minor triads are triangles: upwards-pointing for major, downwards pointing for minor.
I can’t find much on the name and origin of the Gerhard layout. Neighbouring keys are 1, 3 or 4 semitones apart, which brings the major and minor triads into a small arc shape.
This layout is not ismorphic. Every second row has some ‘dead keys’ between the ‘black keys’ of a traditional piano. Two octaves are stacked vertically to get at least two and a half octaves out of this rather coarse layout.