Recently made this playlist of tracks featuring experimental/custom instruments and interesting found sounds/field recordings. Found some gems along the way:
Would love to find more tracks like this if anyone has some recommendations? Set up a collaborative playlist here too.
Biophilia’s good for this, tesla coils, gravity pendulum harps, sharpsichord, gameleste etc.
I heard a track on the radio this week by Chris Watson (from Cabaret Voltaire) who recorded the sounds of sunset to sunrise in the Kalahari desert- it only caught my attentiion because i’m immature and he titled it ‘midnight at the oasis’ !
But this and the other track on the record might be up your street… https://chriswatsonreleases.bandcamp.com/album/cross-pollination
Chris Watson is amazing!
I love Muslimgauze’s atmospheric found sound stuff:
Nice! Thanks for the suggestions, digging this Chris Watson record! 
Eric Holm’s two albums so far, the first of which (Andoya) is based on field recordings of telegraph wires and the second, barotrauma, on subsea equipment noises in Nordic fjords. Pretty obscure.