I am always on the lookout for cylindrical shaped objects that I can adapt to use with different sized thread spool holes. I have used old pen shells that I've cut down , I have straws wound with tape ...my favorite by far is a dritz thread holder that I took apart and repurposed..
http://www.amazon.com/Dritz-920-Cone...B69X47HHKCPEM5
the small cones are angled so they fit up into a variety of different spool sizes...just keep looking at things differently, and you will find the perfect thing!!