If I were to build a device for tanks that can hold 120 film (and I have given this some consideration), I'd make sure it would be roller type, not inversion/tilt type. It has always struck me that one has to prepare 500ml for a single roll of film, and with a roller tank system one could reduce this to 250ml or less. And I would likely do without the pump system, cleaning out the tubing would likely require more effort than pouring the liquids by hand, at least for low volume processing.