

Secret Knock Detecting Door Lock - brentcappello
http://grathio.com/
How many times have you seen a secret hideout with a secret knock?  It's a staple of cheesy dramas, Saturday afternoon movies, and tree houses throughout the world. Now it's real.
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bockris
dup. but under a different source URL.

<http://news.ycombinator.com/item?id=924237>

