I haven’t cut it yet, I’m just looking at the pattern and then sketched it out on paper to make sure my mental folds weren’t playing tricks on me.
Looking at the photo, it looks like you’d take both pieces of material that get cut out, fold each in half on the narrow notches, wrap the small one around the outside, and then stitch through all four panels. Doing that, the cut holes on the top two layers will line up with each other, and the back two layers will line up with each other, but I’d think you’d need the slits on all four to line up…
The top two and the back two layers together will make an X instead of a single direction aligned slit all the way through all four layers of material. I’d imagine it’ll still work, but it seems like you’d want them all lined up for a material like leather. Other patterns I’ve seen generally flip the angle on the fold to line up.
Representing it in ascii, the current hole pattern on both pieces of material, and on both edges (fold on the vertical bar) is:
o / / / / / o | o / / / / / o
So, folded, the slits line up like this:
o X X X X X o
I’d expect it to be something like:
o / / / / / o | o \ \ \ \ \ o
so folded would come out as:
o / / / / / o
But again, first time to sew leather, I may just be making a dramatically inaccurate assumption.