rapid processor
Rapid color processor
That looks a great deal like the processor we used back in the late 60s and 70s for processing Kodaks Tri Mask. A color film designed to mask graphic arts separation negatives instead of several silver masks ( it didnt work out very well) But basically in total darkness the film ,and I suppose paper, was mounted on the outside of the drum the film rotated through the processing solutions again in total darkness. I dont remember how we changed solutions though. In the end working in trays was easier!