Film sources for slitting to Minox format?

I've just ordered a Minox B, several cassettes of film, and a developing tank. The cost of film, however, reinforces my existing desire to slit my own.

I've seen many slitters that convert 35 mm (two strips and discard the perfs) or 16 mm (one central strip, discard perfs), but I don't recall seeing any that do the really economical thing: cut five or six Minox strips out of a 120 roll, to get 10 or 12 loads (after cutting the length in half). Is this because of the difficulty of threading the 120 film into a slitter in the dark, or because there's some physical reason 120 film won't work in the Minox cassette or camera?

I had several slitters made for me, 2 for 120 film. It is possible to slit 16mm and/or Minox film from 120. I slit in a changing back. If you leave just 10mm of 120 film unslit, introduce it into the slitter, close it and then begin to pull, it is easy. With 3D printing and Exacto knife standard blades you can build slitters to your need. As you said, half of a slit fits into a Minox cassette.

I'm not at home at the moment, but I will be back next week and I can post some photos.

I've used the 15+ mm offcut from making 127 from 120 to reload Minolta 16 format cassettes, works great -- but I'm well aware Minox is a different animal from Minolta 16, and wasn't sure how sensitive it is to film base thickness (120 is very slightly thicker base than 35mm, AFAIK). I have (my own design) a 120/127 and 120/3x16 mm slitter that I 3D printed, and if I get my printer going again I could print another blade plate for it that cuts Minox. I'd start it on the paper leader and pull the whole roll through onto another spool, that would help keep things neat.

I've read that Minox cameras are critical on film width, which is where I'd be concerned with a 3D printed slitter. I've sent an email inquiry to Jimmy Li who at least used to make some very nice rolling shear slitters.

I cut 35mm bulk film down instead of film out of cassettes, but obviously cutting down from 120 would be more economical.

The dude from subclub (xkaes? on here) sells slitters in whatever size you want. The biggest issue shooting Minox is getting the cassettes. In the past I've bought them in bulk off Ebay. I think someone sells them (Bluemoon?). You can use either the old metal or the newer plastic ones in the B. The plastic ones are easier to reload but they only hold 36. Metal ones hold 50. Metal ones don't work in the later models.

Thickness shouldn't be an issue. Thinner films will have less space between frames due to the way Minox spaces frames. The width though is important. I can't remember all the measurements I've taken but you should probably limit the width to 9.2mm. Some of the older films were slightly wider IIRC, up to 9.5mm. I made one years ago that is 9.3.

The Jimmy Li slitters shear the film with rollers, rather than using blades; they've got a reputation for precision and durability -- but I've known about Sub Club for a long time, too (I already had years of shooting Minolta 16 when the Web became easily accessible).

Blue Moon sells only loaded cassettes, as far as I've seen -- they claim they're all new cassettes from Minox directly. I ordered four rolls of film, so I'll get four cassettes and their coffin cases -- and, after developing, an opportunity to measure the strip they load. I'll dig on eBay for a couple metal cassettes once I've got the details covered (especially ways to scan and/or print the negatives) -- I don't foresee a lot of need for 50 exposure rolls, but having the option would be good. A full length strip from 120 is a little longer than a 50 roll, if I'm counting correctly (roundly half an inch per frame -- 11 mm plus 2-3 gutter between -- gives 12 inches for 24, 18 for 36, and 25 for 50, but of course you need a couple inches extra at each end for loading the cassette and keeping the tail under control).

What I've read is that nominal film width is 9.2 mm, and some cassettes have more tolerance for over-width film strips than others.

And of course, being able to shoot the finest grained films available for only a couple bucks a load vs. above $15 for a roll for Fomapan is one of the reasons I've kept after getting a Minox.