Inspired by the DDC Stuff Sheath. But dumber.
My intent here is not to take money away from DDC. I actually had a use in mind for this when I made it.
I have mentioned here before that I’m typically a front pocket guy. About all that I typically carry in my back pocket is a handkerchief, and maybe the odd receipt. But then on the cusp of 2018 I thought it would be nice to have both a yearly planner and my current EDC notebook on me at all times. I didn’t want to cram another notebook into my front pockets, and I didn’t want to subject a notebook to the unpleasantness of a back pocket without some protection, and I didn’t want to spring for the DDC Stuff Sheath until I knew if I could tolerate having a notebook back there – and until I knew if the notebook would survive, sheath or no sheath. Hence this zero-cost option, fittingly made from a Field Notes shipping envelope.
I’ll let you know how it turns out.
Echo Station 5-7 
So, how did the DIY stuff sheath work out?
I was considering trying making one with chip bag material backed with Duck tape, just to see how I liked it.
How was your version?
It worked okay, but only okay. I made it to the same dimensions of the DDC Stuff Sheath, and I made it flat. That was a mistake. Leather is a bit more stretchy and deformable than cardboard and packing tape, and whereas the actual DDC Stuff Sheath will hold a couple of notebooks securely, my cardboard version can only hold one. If I was doing it over, I’d stack up the intended cargo load, bend the cardboard sheath around that, and then trace the margins to cut it down to. Chip bag material and duck tape would probably work just fine.
On the other hand, it convinced me that I could survive with a notebook in my back pocket, and that a notebook in my back pocket could survive me. So I did eventually spring for the DDC version.
I still keep the cardboard version around to stuff loose stuff into, so it’s having a successful second career outside my hip pocket.