To prevent rust from forming on tools in your drawers or tool chest, all you need is a block of camphor and a plastic film canister. Camphor is available from pharmacies in segmented 2″ x 2″ blocks. Just drill a few 1/4″-diameter holes in a canister, stick a quarter of the camphor block inside and cap it.
Store one of these little canisters wherever you keep metal tools. The camphor fumes form a molecular film on metal surfaces that retards rust. A quarter block lasts about a year and will treat several drawers or a whole toolbox. When the camphor smell disappears, you’ll know it’s time for a fresh piece.