Thread comes in many lovely colors and sizes of spools but I don’t always need a full cone (at $35 each) of a color. And I have a lot of smaller spools but they do not work well on the Gammill. The thread catches on the small slot intended to corral the thread from unwinding itself all over the floor.
One of my sons solved this problem. We designed a spool cap that would fit over the top of the spool and prevent catching in the slot. It worked absolutely perfectly.
Now I can use a lot of different threads and not necessarily invest in a lot of cones of thread.