The supplies you need for the book compartment are as shown:
-a thick book
Step 1: Step 1
You first want to glue all the outside pages together then when that dry you want to start cutting out the center. Then when your done with that your book should look like this.
Step 2: Step 2
You will then want to glue the next inside pages together.
Step 3: Step 3 Arduino
The Adriano will be hidden inside the book and these are the materials you will need.
(1) analog sensor (a photocell will do)
(1) 10K ohm resistor
(1) 220 ohm resistor
This is the link to the code that you will need a computer to download it.
Step 4: Step 4 Arduino
Once you get everything downloaded and working you put the arduino in the center of the book with a battery so it works. Like so.
Now you have created a hidden book compartment with a photocell arduino with a led light.