How about a series of plastic, ladder-like links which hook together to form a chain.

This plastic chain would be wound up on the reels with the film to act as a spacer to let the chemistry circulate around the film.

After that, we need to be sure we have the correct color filters of quality to do the job, a standardized light source and a repeatable formula for chemistry and it *MIGHT* be possible to do this in your basement.

We're not out of the woods yet, though. Still have things to work out... Still thinking...

P.S. -- The Morse G-3 developing tank: