A tip for other DIY types
If you're looking to build some kind of rotary processor, I found a cheap way to get ball bearings for the shafts for the wheels that support the drum. As the fidget spinner craze has died, stores are selling them off dirt cheap. I bought 8 at Ollie's for a buck each, There are 3 bearings with a 1/4 diameter hole in the center of the bearing and the center bearing from the spinner is smaller. Other brands of spinners have different center ID's-if you shop around you might just find what you need for cheap.
Re: A tip for other DIY types
You can buy ball bearings at bike shop's too for quite cheap if the standard bearing sizes line up to what you need.
Re: A tip for other DIY types
Eventually my Cibachrome drum roller will give out. I am not a handyman, though I have made a couple of small rolling video dollies (not motorized) with skate wheels and PVC, almost accurately. If anyone comes up with a fairly easily constructable roller for someone without such tools as a drill press or lathe, or electrical knowledge, I'm sure a number of us would be grateful.
I use one of the Jobo tanks for 4x5; I don't have the number here. It holds two reels which each hold 6 sheets. It works fine on the Ciba roller.