It does bring back to mind an early experience I had developing film, which involved a heavy ceramic roller half-immersed in a bath of developer. You looped the film under the roller, held one end of the film in one hand and the other in the other, then ran the film through the developer by raising and lowering your hands left-and-right. In darkness, of course. I remember doing this a few times, seemed to work OK. I've often thought of using PVC pipe to build a super-sized Minox-like tank that would take 35mm film, emulsion outwards. Something to look forward to in retirement!