I use the small woven pony tail holders for bobbins. I don't keep them with spools of thread. For my sewing box, I use one those notebook rings that snap open. The rings hold about 6 bobbins. Pre-wound bobbins are a ring also. Other bobbins are kept in either a bobbin ring or bobbin holder.
Bobbin notions here.
http://www.nancysnotions.com/categor...ies/bobbins.do