Remixed this based on existing spool weights to support Sunlu 250gram / .25kg 120mm spools with 42mm holes, that I was using with my small spool adapter.
They fit fine in using the spool adapter but without a little more weight behind them, they had a habit of jumping and not retracting well on the forward rollers. Printed up a couple of these and filled with some loose-change/nuts/screws/etc that have laying around that gives it a good weight and no longer having any issues.