I also just remembered about a concept shown on Hackaday, whicg uses 'pogo-pins' (spring loaded pins), placed horizontally which can be retracted and the esp-12 pushed into place against the pin's tension. The other end of each pin soldered onto a stripboard. I have in fact seen a few variations and also some other designs for other microprocessors. Again I have not seen any commercial product, and they would not be quick to mass-produce manually by a hobbyist. The pins are cheap to buy and one day I may make a board.
My idea was to have protruding pads (basically solder nipples) on a board which locate on the esp's castellations, then have a spring clip on top to tension the chip onto the board's pads. It would be much quicker and cheaper to make. Perhaps some entrepreneur could propose a design and sell it??