I recently performed the compositions to observe sea and sky by Donald Bousted. He wrote it for the flute to play in 12 equal divisions of the octave (standard tuning) and the horn in 19 equal divisions of the octave. This combination worked well and I got to thinking about how close the divisions of 19 are to dividing a whole tone into 3 parts. This gives 18 divisions of the octave, basically a modified whole tone scale. I don't really want to write in whole tone scales, though of course there are only two required to provide a standard 12-tone chromatic scale.
One of the issues I deal with is writing for standard instruments and I am working on writing a piece for trumpet to be potentially performed in a high school final exam. Often in such exam situations a performer likes to work with piano in part for support both energetically and in sound, in part for the musical interaction and in part because the piano can give the other player a rest from time to time. My next thought about the possibilities a player could have when using a standard trumpet with movable 1st and 3rd valve slides. It seems to me that a trumpeter could play 1/6th tone variations of all chromatic notes in the middle octave reasonably easily. Donald Bousted and Stephen Altoft have shown how the standard trumpet can provide 1/4 tones, though not at great speed (https://donaldbousted.com/2015/08/22/the-4-valve-microtonal-trumpet/). So, I'll have to be careful how I write for a trumpet which is essentially playing 36 divisions of the octave.
The piano provides pitch stability over 12 tones each octave and the trumpet can provide additional pitches. So here is a computer generated audio extract (using Dorico notation program), from my first steps into this realm: the first 40 seconds of a piece called Epictetus (named after the great Greek philosopher.
01_Epictetus_first_40_seconds.mp3
Here is the example in notation.
