I prefer to clip my filament to the side of the spool but I have never found one that fits all my different spools. So I made one. This fits all my spools from just over 1mm thick wall ( as you can see in the posted photos ), to 3mm plus. The small tags on the clip help to put it on to thicker spools but generally just fits straight on. The print is barely 2 grams and less than 6minutes per clip. They grip solidly to the spool walls and has a satisfying click when pushing the filament into the holder. PLA works great but if you are going to continually swap between thick and thin spools PETG may be a better, more flexible choice. Thanks for looking.