Did you realise the end caps come off Gutermann 100 metre thread reels (7 grams) so you can wrap the end of your thread around it… or that you can store a needle inside the reel? There is quite a wide choice of different threads for various purposes (including a transparent one). If stored in a small snap-lock bag to keep it clean, it could easily be dipped in some methylated spirits to sterilise it for sewing up wounds. Of course it is great for rep[airs to clothing, gear, etc. The stronger threads would be useful in an emergency for catching small fish. You could sharpen a stick and force it on the lid end to make a small caster. (Some hooks etc would also store in the middle- you may want to tape the end a little more securely though. The paper end sticker may come off.)
