SpoolPod your new best friend
SpoolPod lets you store 9 thread spools and their matching bobbins. It stacks to go in drawers and on shelves, it’s flexible (stash it in a bag?), and will generally make you feel like an organisational ninja.
Try one for size, or for prime Pinterest-perfection a pack of 5.
The individual pods are 1.8cm x 7.7cm and stretch a little. Sorry the thread isn’t included