Years ago we made boards with only a ground and power layers. (pads and holes) All the signal traces were "transformer wire" (paint insulation).
There was a machine that welded the wires to the pad, then ran the wire across the board to the next pad and welded then cut the wire. At the end the board was covered with clear paint to hold the wires in place. (no parts on the board while welding)
It was something like wire wrap. No sockets.
Sorry I can't remember what it was called. Have not seen it for 40 years. Well this is not helping you.