Search Tone2 arduino on Google and get the instructions for it. Tone2 is a code for an alarm sounded by light.
Step 1: Stick It to the Inside of the Box
Tape the arduino and bread board to the top or bottom of the inside of the box. You con also use glue.
Step 2: Find a Power Source and You Will Be Done
one you have the power source, the alarm will go off whenever you open it, and when you close it, it will shut off. You can use it to hide almost anything and I don't know about you, but I'm using this to hide my shoes away from my brother he tries to wear my shoes without asking me. So, every time he opens it, an alarm will sound.
I will show you the box I am going to put it in on the next pictur.
Step 3: THE BOX
This is how big the box is going to be.