Fingermarks Sound Design has released Drone Machines for Madrona Labs Aalto synthesiser.
This bank of 85 presets for the Buchla-inspired Aalto synthesiser is comprised largely of self generating sounds that drift and evolve slowly (somewhat like Metaphysical Function but synthesised, not based on samples). These are not typical "bread and butter" sounds but mostly subtle sounds that invite quiet contemplation or that create droning, shifting, walls of soundscape. Most can just be left to run, others can also be played using the keys and will interact with the player. There are also a few pads and bell-like sounds as well. Several sounds also have more than one variation.
Price is on a pay-what-you-like basis with minimum of $5. Available here.