Most people own at least a handful of locks. But what happens inside of them to keep our things secure?

In this episode of Make: Inventions, we look at the pin tumbler lock, the most popular and enduring lock design of the last 150 years. Along the way I show how I built a working, transparent model to reveal its secrets.

This video features patent #31,278 “Post-Office Drawer Lock” by Linus Yale Sr.

See all projects in the series here.