Know those records that you insert into a vinyl record player? Basically those, but pirated since a real one costs money when you purchase them at official music retailers. It involves the process of obtaining a legal copy then using wax molds (to recreate a record) and specialized tools (prevent quality loss) duplicating the record. (Also, “Bone Music” existed in the Soviet Union by printing music by using x-ray films).
I don’t remember ever hearing of anyone copying vinyl records by direct impressioning like that. People made tape cassette copies all the time, and you could buy illicit cassettes from street vendors in lots of places. I think if someone wanted to make illicit vinyl records, they’d playback the original one the normal way, use the playback to cut a new acetate master on a cutting machine, and press copies from that.
LP cutting machines were professional studio equipment, bigger and more expensive than a typical hobbyist would have at home, but not THAT expensive in the world of other studio gear. The actual presses were industrial equipment and maybe you’d need a special relationship to get a legitimate one to press your pirate LP’s in volume. I expect that a suitable envelope of cash could create such a relationship quickly, but I was never anywhere near anything like that.