Central ring eSun cardboard spool - Improved flow

Central ring for eSun cardboard spools, helps the spool rolling while mounted externally (mostly for TPUs). --- I spent harsh days trying to have a decent flow with eSun spools since they're somewhat sticky on the inner edges and this makes friction on the external mount behind my P1S.Maybe there are other models like this but I wanted to do something minimal and efficient so I designed and printed it myself.