Wind screen for small stoves and candles, keeping the plastic carefully away from high heat.

Ala Mr. Samuel Thayer, create right size hole to fit over cattail heads which are then "knocked" to collect highly nutitious pollen inside a clean, dry container.

Filled bottles can act as weights to close traps and trap doors after the traps are triggered.

Sun- or fire-warmed water-filled bottles as the classic hot water bottle.

Rigged with lines, hoses, or tarp "gutters" running to their mouths: rain water collectors.