hello! thank you for your kind comment and interest in the soundtrack! i was the composer for "co-open" so i can answer your question. most of the instruments in the OST were made using the ableton sampler and putting field recordings i had made into it. i used EQ to boost 440Hz (an 'A' note) of the audio source. this gives the sound both interesting texture, and harmonic elements to make melodies. this video goes in depth about it if you're interested in trying it out. i also used ableton's operator FM synth, synth string samples, sine waves and various other sounds. if you have more questions feel free to contact me! my contact info is on my website which is linked on my itch.io profile :)
Thank you so much for the response! That's such an interesting way to make unique instruments! This helps me a LOT, because I've been experimenting with Meld and Operator for a while (maybe not as gracefully as others, but I'm getting there!) trying to see what kind of sounds I could conjure up, and it's very fun, but the idea of taking samples and then turning them into instruments feels like an entirely new layer! I'll definitely be watching that video, thank you :D