It is a good idea! Thieves, pls don't search my yard for pinecones! Here's a good idea to hide your extra house key - put it in a medicine bottle, glue a pinecone or rock on top, stick the bottle in the yard or planter.
9 Geocaching tools to keep in your pack (also add gloves, headlamp, and a stick/pokey thing to poke before sticking your hand in something, oh, and a grabber thingey & mosquito repellant) (ah the professional equipment)
This is such a fun idea! or use dremel tool on a real brick. Perhaps a small real Lock & Lock could be used instead of a film canister. Would be watertight and more fun to be able to leave signature items and travelbugs.