I don't carry many keys, but there are three that I do need with me at all times. Unfortunately, those few keys have scratched a couple of expensive phone screens over the years, when I've inadvertently jammed them together in the same pocket. Sound familiar?

I thought I'd solved the problem when I got one of those Swiss Army-style key cases, but those didn't keep things as locked in as I'd   hoped, and I lost another screen protector.

Sigh. 

But then last night, I had a brainwave. Keys are pretty flat… Why not keep them with my credit cards? So I ran home and designed this.

Now they come with me wherever I go, they're easy to access, and they cannot scratch my phone ever again. Plus, it's one less thing to keep track of in my pockets before I leave the house. 

I've also made one for my kid, who seems to lose their house key every other Tuesday but has managed to keep their wallet safe for years.

Caveat: Keys come in a bewildering assortment of sizes and shapes, so there is virtually no chance that the STL I've included will suit your key life out of the box, but you should be able to customize the OpenSCAD file in just a few minutes. There are instruction comments in the file.

Mine is printed at 0.3mm layers, with 2 perimeters in PLA and took about an hour on an MK3S+. It needs to be printed standing up on the long edge so it can print without supports inside. (Although I did use organic supports for the extreme circular overhangs.)