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 I have a few very outdated 110 films and cannibalised them, dumped the film and re-loaded with cut-down 35mm FP4 backed with the original paper.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.
Originally Posted by kb3lms
The main thing is to have fun!