The technique of the composition I use in a Mandala is one that give a work an imaginary symmetrical pattern. It is similar to what Pauline Oliveros did in her horn etudes (1959) where the composer limits oneself to only a few melodic intervals.
I also have an in-passing rule, where if you go one direction with an allowed interval you may go in the opposite direction skipping the previous tone, but jumping to an allowed interval based one the previous tone. This rule is good at creating hyperbola shapes in the music.
Opus 58 Mandala No. 3 for horn and violin
Opus 119 Finding the Mandala for two horns
Opus 149 Horn Quartet No. 4 "Amram visits Copland's Tomb"
Opus 163 Mandala No. 4 for horn and violin
I used half or whole steps and major or minor thirds in this mandala. Along with the interval limitations, I also bind myself with I Ching scale limitations, using I Ching No. 36 "Censorship".