Just gotta make sure you cover the gaps between the slices with opaque tape (or skinnier slices of backing paper). Helps to have a local lab who saves it for me. Not sure how I'm gonna get the frame numbers in the right places yet.
In any case, 127 is unnecessary, you can just slit down 120.
(edit: kind of looks like a necktie, doesn't it?)
Good craft shop for all black paper and white China ink?