Although I don't sell pens, I do keep track of them, ID (Serial Number), style, blank material, and I even assign a value (Price?) primarily based on my estimation of the rarity of the materials and the overall finished appearance - maybe it's more of a rating system of how much I value the pen more than anything.
The ID number is my key into an Excel spreadsheet where I store the specifics of the build, the date, materials, notes, the drawer and slot I have it stored in, and such.
I tried the string tie labels and I didn't like them because they don't fit in my storage drawers very well - they get tangled with adjacent pens. I also tried using the barbell labels but the one's I had were not computer printable so all I could get on them was the ID number. That and I struggled getting the sides aligned when installing them.
So, ultimately I wound up printing the ID number, the value, the style, and the blank material information on half of a return address label (they are 1.75" x 0.5" - Avery #8167 or Online Labels OL25 and apply it by rolling it around a 3/4" piece of plastic drinking straw. Then I simply slip the straw onto the clip. It is compact and still contains more information than just an ID number. As for ID numbers, I just use a serial number with no embedded information. I like it because it is compact, easily installed or removed, and doesn't leave any kind of sticky residue behind.
Here is a screen capture of one of the labels (I use an older version of Microsoft Publisher and just print them on my inkjet printer). The fonts are 7 point for the ID number, 8 point for the Value, and 6 point for the pen type and blank material.
Dave
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