Here's one sneaky geocaching container: a magnetic "rusty" bolt! The bolt is hollowed out for a log sheet, and the magnet is secured in the top of the nut.

When threaded together it looks like an old bolt that belongs on a rusty surface. The strong magnet holds it firmly in place and the rubber seal keeps the log dry. 

Attach this to a rusty metal surface and watch those favourite Geocaching.com points add up. This is one great creative hide! Two waterproof logsheets are included with each geocache container.