The way I understand it. 35mm is different from 120mm which is different from sheet film.
You don't need to fit sheet film in a 35mm can. So you can't make it exactly the same.
I thought somebody said getting Ilford to custom cut film wasn't too expensive. The problem was the massive order size. Likely no different then Kodak. You aren't really paying for the film but for setting up the machine. If you buy enough the cost of setup gets spread over enough sheets so it's not an issue. But if Kodak/Ilford/etc had to change the machine over a few boxes it doesn't make sense for anybody.
What might make sense is a buying co-op. It doesn't even need a lot of effort on our part. [Always a good thing-))] Does anybody have good contacts with any of the major retailers? All it takes is a retailer willing to take orders. When x boxes of a certain size of film are ordered then the order is sent out to have the film made.
Buying a plant sounds nice but some how I wonder if it would turn out to be a "I love Lucy" episode-) Instead of buying a whole plant buying part of it's production might be easier. Something like committing to buying so much film every year for so many years.