I got lost in my refills so I created this nametag. It can be always on a spool or if you take the filament off you can secure it with a ziptie.

It is designed to fit in any of the three holes in the Master spool by Anachronist, the great Spoolmaker.

In the slicer you just add a name (ex. Fiberlogy PETG or you can even call it Steve - endless possibilities).

I used a MMU but there is just 1 filament swap so the manual change is very simple. You can also print it in one color and use a marker to make the letters visible.

ABS, PET-G and PLA are all tested and equally fine.

Below you can find somewhat parametric design in Onshape - just edit Spool_thickness and Hole_width variabes (I hope it'll work fine):

https://cad.onshape.com/documents/a3d500e308d21c8edfe408d1/w/05810f0715d57f48b21d368d/e/a3ea25a4b4ea9e2864b4495d?renderMode=0&uiState=65c20db08422c86f54fe9db8