how to get múm/Ricky Eat Acid sound?

the very beautiful crackling synth at the beginning of sleep/swim and the gorgeous ricky eat acid sound in "inside my house; some place i keep dreaming about". i'm satisfied with at least knowing what the ricky eat acid sound is. it sounds like a rain forest to me at times idk it's just incomprehensible and mysterious but very beautiful https://www.youtube.com/watch?v=chFmFpTc21s https://www.youtube.com/watch?v=DoYf7wiZdTo