Aside from the Janko keyboard, there are instruments with the ‘harmonic table’ layout—a honeycomb of hexagonal keys: https://en.wikipedia.org/wiki/Harmonic_tabl

Aside from the Janko keyboard, there are instruments with the ‘harmonic table’ layout—a honeycomb of hexagonal keys: https://en.wikipedia.org/wiki/Harmonic_table_note_layout https://en.wikipedia.org/wiki/Harmonic_table_note_layout The general principle is called ‘isomorphic keyboard’: https://en.m.wikipedia.org/wiki/Isomorphic_keyboard https://en.m.wikipedia.org/wiki/Isomorphic_keyboard