That's an aircraft grade rivnut and an aircraft grade machine screw. The rest is self-explanatory.
That's a really good idea. I think I'll show it to my father in law. He carries an entirely separate wallet to hold all of his keys. It's amazing how much stuff he lugs around. This could only help. Also, you should post this and any other creations in our "Give me your spam" post. -It's not what you think... it's a post for all of us to share what we work on etc.
Well, this was done entirely with hand tools, with the exception of trimming the keys off! You could make yourself a neat little hand-tool shop in a closet, if you wanted!
I know, I have a small closet with a tool box. I used it for a couple of months as a grow area (ahem). Now it's too hot and humid to do any work in there. Still some things need better tools in order to be made. BTW I hate keys. In my last apartment we replaced the front door with a fingerprint one. Our current house only has one key.