When you do the secret knock, it gives you some candy.
This is my version of the Secret Knock Gumball Machine
by Steve Hoefer. I used his circuit and his code, but I struck out on my own for the mechanical design. This was my first time working with acrylic, and I did a rather poor job on many of the details. But it was fun!
I offer these pictures merely for the design inspiration. Maybe it will give you some ideas. I'm glad to answer specific questions about how I put this together. Hint: I didn't glue any of the acrylic together.