I purchased an old engineers metal storage cupboard that is just about the same size as the very expensive professional film dryers. After washing it to remove the years of accumulated grime I lined it out with thin polystyrene and installed a small tube type 100watt greenhouse heater. I attached nylon cord similar to that used to start a chain saw, in rows along the top to hang the film. I can dry 12 rolls of film or 9 4 x 5 sheets. The total cost was 25 pounds sterling.