When switching lenses on my camera the other day, I looked at the lens and the camera caps and thought to myself, Hm, I wonder if I can use them as an improvised SD card case? And you know what? I actually can.
Turned out, two SD cards fit neatly into the rear lens cap. And with the camera cap screwed firmly on top of it, I have a small and sturdy card case I can carry in a pocket. I use caps for Nikon F mount, but I'm reasonably sure that other caps should work too.
content creator YouTuber could probably turn a simple hack like this into a 30-min video. But I write words, so I stop here, because there is not much else to add.