Make Yourself This Secure, Lock-Free UnaBox
“While it might not be the perfect solution for the truly invaluable items you own, a box you unlock with your own intellect is a surprisingly safe way to store your important belongings. MAKE Magazine can show you how to make one.
To create your own UnaBox, you’ll need a few woodworking skills—nothing you couldn’t have picked up in middle school wood shop—but overall this project is considered to be an easy one. It involves very simple construction and then only requires you learn how to open it.”
Update (14 Aug 2011):
You can find a video of this project at Dailymotion