Thanks everyone for the feedback, and to seall, John and Jim_jm for the extra information.

To Alan, Oren, Dave regarding the “why”... it’s nothing revolutionary (pardon the pun )...

I want to make a manual rotary processing contraption for my black and white 4x5 sheet film. In terms of throughput, I don’t need to be able to do more than 2-4 sheets at a time. Also, I’m used to processing in the dark and have never minded it so I don’t need this thing to be daylight-safe.

Picture two of these open-ended, slightly barrel-shaped tubes, side by side, roughly 1/3-1/2 submerged (horizontally) in a tray of solution, and rotating in a controlled way by some sort of hand crank. Each tube is just 5” in length. Easiest would be to have just one sheet in a tube, but I suppose a slightly wider tube with some divider “fins” could accommodate two sheets.

You move this mechanical assembly from tray to tray.

I imagine the rotation to be like a Jobo - ie say in the 50rpm range (but it could be whatever you want) and reversing every few revolutions.

I want the “tubes” to have this slightly bowed, barrel shape for two primary reasons:

1. The solutions get to the base side of the film, eliminating any potential issues with anti-halation dye

2. Minimal contact between the film and the tube means lower risk of scratching or weird contact artifacts

I considered a vertical variant of this, which might be easier to build, but that obviously means the tubes/film are fully submerged the entire time, and I don’t know if this type of rotary development would work. It would have to be carefully tested for uniformity.