Secret Knock Box

The SECRET KNOCK BOX is a keepsake box that only opens when its owner taps their custom secret knock. The knock can be reprogrammed at any time. The box is powered by 3 AAA batteries, and uses an Arduino Pro Mini, a piezo pickup (knock detector), a sub micro servo (latch release), and custom 3D printed and laser-cut parts.

The Arduino code (sketch) contains code from Secret-Knock Gumball Machine written by Steve Hoefer, used with permission. Steve’s Gumball Machine was the first Arduino proje