Here are just a quick couple of things I thought might be useful ideas for box tops & swizzle sticks.
Small box top flaps make good starters for yarn balls, especially the slot side of the tab closing boxes. (Does that make sense? I feel I lack the appropriate vocabulary for discussing box tops.) It can be done with any cardboard, but those bits of flap require the least amount of effort to be useful.
A wholly unnecessary photo tutorial on how to turn box top flaps into yarn winders: