There are many out there but I made this one in Tinkercad designed around the thread tag so it would not need to be trimmed down when adding thread. There is a slight pitch to the thread area to keep from hanging up while using and possibly cutting the thread AND a pause in the model print halfway to add an NFC tag for easy re-orders when running low on the corresponding color. Finally, a strengthening ring around the binder area keeps it from breaking easily when flipping through your thread colors.