I use small pieces of cardboard for my sewing, fishline and GPS (general purpose string). Each of these lay flat in their respective kits in the BOB. You can get an amazing amount of feet of thread/line/string wrapped on in no time...



Also if you look closely at the black thread, you will see 2 needles embedded into the cardboard, You do not have to worry about them falling out when opening the sewing kit.

For my sewing kit and fishing kits, I use small, flat and clear plastic containers that wood/metal screws come in. They are virually indestructable and more or less free...