Usually I use any permanent pen I have close at hand to make a label. I've used Sharpies, Pigma pens, etc. Anything that is permanent & won't bleed! I've also printed a label on my computer, then drawn over the lines with my pigma pens & colored in the image & then sewn it on the back of my quilt. Sometimes I just write right on the back if I've used a fabric that reads as a 'solid'. Do what makes you happy! :D
sue