I use a folded over tag, probably a bit too big, but it works. On the inside is an instruction on how to change the refill, and on the front is my business logo. On the back is the type of pen, wood type, and serial number. I print these on cover stock, just a bit thinner than card stock, but heavier than regular paper. I just print them off a page at a time, and flip the paper over to print the other side. I have a file for each type of pen I make in both wood and acrylic. I cut them out with some "Ragged Edge" type shears, and try to give them a folksy look. I fold them over, punch a hole in the corner, and tie them to the drawstring of the pouch, or attach the string to the pen. I made one for the first pen I donated, and everybody after that started asking for them. Now, I find that they are a big selling point for me. Now, I am starting to include them with my calls, and bobbins.