I took a big metal box with tea leaves inside and applied constant rotating motion to it. Can be looped perhaps. Hint: it was recorded at 96 khz, try playing this at 41,1 khz, sounds interesting. Recorded with zoom h1. No postprocessing.
Old socialistic circular saw from northern czech republic. Recorded at the end of october 2015, the best was to have recorder in next room. Recording was made on h1 zoom handy recorder and edited in professional sound studio (motor was filtered off).
