I purchase small plastic bags from the jewelry craft area a WalMart. I put my spool of thread and bobbin in one bag together. They are then stored in a plastic box. It works because it keeps my thread and bobbin together and they do not get tangled. I do this with all my threads because I transport them to guild and UFO's. The plastic bags come in various sizes, but WalMart only has a couple of them. Hobby Lobby has a large number of sizes. They are not expensive and I use the larger ones to store and transport my cut squares for piecing.