PocketMod wallet

Earlier this week I wrote about a slim pocket notebook cover I 3D printed from TPU filament. I tend to use that notebook for longer notes: full sentences, paragraphs, and more exploratory mathematical diversions. For smaller notes, like names, dates, to-dos, and quick calculations, I use a PocketMod.

I source PocketMod pages from the same stack of scrap paper as the half sheets for the pocket notebook, but I don't care if one side is completely printed so long as the other is mostly blank. On occasions when the opposite side does have some blank space, I can flip the fold inside out to get additional writing space.

I tried carrying a bare PocketMod, but despite the thickness of the folded paper, my pocket still gave it wrinkles that made the paper difficult to write on. For a long time I used a thin piece of cardboard cut to the same size as the PocketMod and held on with a tiny binder clip. That worked alright, though I did lose the occasional binder clip. I worried about the cardboard wearing out, especially at the corners, so I wrapped it in contact paper. The cardboard eventually acquired a curl, which led me to look for alternatives that didn't need a binder clip.

When I asked on Mastodon, one person suggested gluing cardstock to the cover pages to provide a bit of rigidity. I haven't tried that, but it's an interesting idea.

Claude suggested a 3D printed solution and gave me an OpenSCAD file for a PocketMod-sized base and lid, with the lid slightly smaller than the base so it holds on when printed in TPU:

The OpenSCAD file is here. The lid's fit isn't tight, but there's enough friction that I haven't had trouble with it falling off. The lid also fits on the back, so you don't have a second thing to hold when using the paper inside. Most of the time in my pocket I keep the lid on. When I have kept the lid on the back, the lip of the base tends to keep the booklet in place.

The corners of both the lid and base are rounded to let it slide in and out of a pocket more easily. The original design included nubs to hold the PocketMod in, but they didn't work well and I cut them out with a knife.

The wallet works well enough, but I've only been using it a few days. We'll see how long it lasts. It's bulkier than cardboard, but less fiddly than needing a binder clip and easier to stuff with new sheets than gluing on cardstock covers.

It's also fun to have a use for TPU filament. Most prints for TPU seem to be toys, though arguably, this isn't all that different.