For fire start cotton balls with vaseline.
FishING bobber, keep pencil and paper with paper clip, keep part of med kit on it, (blood clotter, super glue and topical antibiotic ) keep actual pill variety in ie anti histamine, pain killers, gravel, lomitol, antibiotic pills ( first few days of a cycle of broad spectrum) , my suture kit for ifak.
A bigger one size of a medium asprine bottle I keep a local plasticized map and micro compass.
One that fits 3 aaa batteries into one tight so they don’t discharge
To id bottles I use abut 1 foot of ductape different colors wrapped around bottles.so it does not impede lid.
They can be used to house weather sensitive chemicals like premixed thermite, powdered magnesium ect.
They make great smoke bombs housing.