I have bobbin cases that I've had for years. I have the greens in one case, reds in another and so on. I also have a case for the heavy duty. Also the number on the spool of thread is matched with the same number on the bobbin. I use the little round adhesive tabs you see on yard sale items. They're cheap and you can get them anywhere in different colors. The small snack size Ziploc bags work well also. They're big enough to hold a couple spools of thread and bobbin spools. Also great for traveling.