That's probably what I will do. I do have some lightweight black opaque construction paper that I think could also work as it seems about the same weight as the real backing paper but I'd have to find it in roll format.
As far as a pattern, I did just win an *Bay auction for an Instamatic 104 with 2 126 cartridges (Kodakcolor II) and paid less than 5 dollars. The film itself is likely worthless but the carts and backing paper will be useful. There are also lots of 110 cameras out there with old film included, too. Many of these camera outfits appear to be unused, NIB.
All this has happened before, and all this will happen again.
Where do you get the backing paper? Do you know of a source for new backing paper (or a substitute) or are you recycling paper from previous 110 carts or 120 rolls? I have been fooling with 126 cameras/cartridges and was trying to figure out what to do as I do not have any actual 126 backing paper.
I've just used the backing paper from 110 carts. I have a few very outdated 110 films and cannibalised them, dumped the film and re-loaded with cut-down 35mm FP4 backed with the original paper. It lasts a long time, but if I needed to make any I'm sure it wouldn't be difficult to slice it down from 120 in a similar way to slicing the film. I use a pair of Stanley blades in a jig with a fat spacer and shims for fine adjustment. A hinged lid clamps everything in place and two guides keep the film straight as it's drawn through.
Well...you'd have to disassemble the film cartridges and re-wrap the film in the backing paper, then reassemble the cartridges properly (all in the dark), in order for it to be an effective light-trap. Probably more trouble than just unloading in the dark.
More to the point, does anyone have a source for C-41 processing of 110 film? I have a few rolls needing processing. Perhaps Dwayne's in Kansas City?