I use plastic binding combs. These are the plastic combs which hold loose leaf binders together as in the photo below. Take them off the binder and they look like this: I went to my hospital print shop and got a bunch of them in all sizes. I cut them to size and they will fit around any size of spool. Here are the ones I use for the spools on my Norvise Bobbins. You can cut them to size to fit any spool including the regular thread spools. For the regular thread spools, cut them so two comb arms wrap around the spool.