If someone asked me, ” as a child, what was your favorite toy?”, I would have to respond, “my Legos”. Legos are the coolest toys. I probably logged thousands of hours over my childhood making cranes with my dad or spaceships or giant robots. In fact, being in my thirties, I still utilize my legos to make prototype designs and to get an idea about scale.
Anyway here is a video and an instructable on how do build a lego combination safe.
instructable – link