Here is a little project which may help you get your keys back in case you ever happen to lose them. They could really be attached to anything you want to tag with a bit of information (pet tag?)
Step 1: Tools That I Used
A list of tools which I used to make this project is as follows
Ball peen hammer
Drill w/ drill bits
Number punch set
You don't necessarily need all these tools and could make this project with just a few of them.
Step 2: Appropriate Material to Use
There is no single material to use and you could likely use any type of material that will be able to lay flat as well as be shaped and stamped.
I decided that I wanted to use some soft copper tube for this project as It should age well and get some neat patina in the nooks and crannys of the stamped numbers and peening. We had some rolls of 1/2" soft copper piping at work, so I cut off a 1/2" long piece of it to use. If you have straight copper pipe, you should be able to use it, but may have to anneal it first. You can anneal it by heating it up red hot and letting it cool slowly.
Picture taken from https://iscrapapp.com/wp-content/uploads/2013/12/1...
Step 3: Cutting and Flattening Out
With my 1/2" long piece of tubing, I just cut it on one side and then proceeded to pry it open and squish it flat in the vise. After I was happy with how flat it was, I annealed it so it would be equally soft across the whole piece (not pictured)
Step 4: Peening / Decoration
This step isn't necessary, but I thought it added some character.
You could decorate the back of the tag however you like. Sand it for a satin look, file in a pattern, paint it, peen it or whatever your imagination can come up with.
I decided to go with peening and tested which peening technique I would like better. In the second picture you can see the difference between a ball peen on the left and a welders chipping hammer on the right. I went with the chipping hammer as I thought it looked better with all the small peens (dents) on this small of a tag. I proceeded to peen one entire side of the tag. This also helped to work harden the material so it will be more resilient while hanging on my key ring.
Step 5: Cleaning Up the Edges
After peening my tag, it was bent and had very rough edges. I flattened it out in the vise once more and proceeded to straighten all the edges with a file. This doesn't take too long and you can start to see what your final tag may look like. You can use the flat side of the file held along an edge to see if there is any high spots which need to be filed down more.
Step 6: Stamping Information
I wanted to have my phone number on my tag so that if I lost my keys, there was a better chance I would get them back. I chose the last 7 digits of my phone number because there are only a few area codes where I live and the number will not give away where I live (in case someone finds my keys and then wants to break in to my house). I started at the last number and started at the end of the tag. For example, if your number was 123-4567, you would start with 7, then 6, etc. This gave me the correct spacing so the tag would be the correct length. We happened to have a hyphen in with our number stamps at work which came in handy. The tag was once again bent up from the stamping, so I flattened it again.
Step 7: Drilling and Final Shaping
I drilled a 1/4" hole in the end by putting it in the vice with a piece of wood for support from the back. The hole was placed far enough away from the info so other keys on the ring would no obscure it. I also left extra copper around the hole so that when the hole wears, the tag would have a longer life before the tag breaks. I then cut the tag down and did the final shaping with a file to round off and smooth all the corners and edges so it would not cut me or my pockets. I also chamfered the drilled hole with a larger drill bit just to make sure there were not any extra burrs that would cut anything. Finally I cleaned it up with a rag and installed it onto my keys.
Step 8: Final Product and Thoughts
I was quite pleased with the look and function of the final product. It was thin, strong, had my info, and barely added any bulk to my keys (I've been trying to minimise what goes in my pocket). If I had thicker material, the peening on the one side would have stayed more consistant, but when the numbers got stamped in, it flattened out a few spots. I made two of these tags for my work keys and personal keys 6 months prior to making this instructable and they have held up extremely well. They have not tarnished and left me with green pockets but have stayed quite clean and not shown any obvious wear.
Thanks for checking out my instructable and feel free to share any thoughts, suggestions and ask any questions you might have. Cheers.