Using the handle included on the “base model” of Cell Spool Winder, I found it difficult to get leverage on the upswing when winding large  spools (spools that were more than half full).  So I noticed that the smallest gear has a 1/4" socket hole embedded into it, so I decided to just make a new bit to go from the handle to the spooler.  Unfortunately, I also needed to shrink down the size of the handle because the smaller gear is lower in the model and the large handle wouldn't make full rotations.  The modified handle doesn't have the circular cutouts like the original handle, and the “grip” also does not rotate because in the interest of time I didn't want to try and figure out how to do a print-in-place design.

Anyway, this is a small handle to get better leverage on the small gear spindle (the TARGET spindle) for when you are hand-winding.

Reference:  https://makerworld.com/en/models/561571-cell-spool-winder