Some guitar looping form 1980. Ran the guitar through a small amp and the amp into the record head of an open-reel tape machine. The tape machine had a shoe tape loop. New playing overwrote existing loop material. Played against an electronic metronome that was looped against itself thru a graphic equalizer using Y cable. Adjust the EQ changed the both the timbre and the amount of feed back (which resulted in various extra clicks, and sometimes proper feedback).
Done around 1980. Recorded on a shitty cassette tape because I had zero foresight and preferred to spend money on beer.