“In this Instructable I am going to show you how to make an Arduino powered Riddlebox. I made this to add a bit of fun to my girlfriends actual christmas present, which I hid inside the compartment of the box.
Once 5V are applied to the USB lead, the Arduino powers on and the LCD shows a short tutorial and then a sequence of ten riddles, which need to be solved to open the servo operated compartment, which can hold a gift or present.
There is also a sneaky, password protected, settings menu for resetting progress and opening the compartment.
I used what I could find at my local hardware store and 3D printed the rest. Obviously you can customise the Riddlebox by adding more sensors or leaving out some parts. Let your creativity run free.”