I read MANY inscrutables & posts and saw that no one had created one like the one I made .

You must have seen many books which have a secret compartment in it.BUT it is DIFFERENT.

You see this approach allows reader to read whole book keeping the secret compartment out of sight. Thus is a TRULY secret book.

Epilog contest:
If I won the Zing laser I would put it to good use!

I will make small mechanical objects for my projects.

The laser cutter would be super useful for making custom parts.

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Arduino nano (preferable) OR any other

servo moter


jumper wires

cardboard for making compartment


Step 2: Get a Book!

First select a book that no-one in their right mind would ever want to read.

You will need a good thick book. Hard back is best but a paperback will also work.

if you are using paper back,then first apply card board on it and then start other steps

Step 3: Starting With Compartment

firstly ..

Dimensions of compartment will depend on size of your book spine.

Design of the compartment is shown in image.

In this compartment ,one place is for arduino and servo moter and other for keeping your things.

Step 4: ARduino Coding

Arduino code is very much easy.

For this you need

arduino software

libraries : Password click here,

keypad here


#include <Password.h>
#include  <Keypad.h>
#include <Servo.h>
Servo myservo; //declares servo
Password password = Password( "14471" );   //password to unlock box, can be changed
const byte ROWS = 4; // Four rows 
const byte COLS = 4; // columns 
// Define the Keymap 
char keys[ROWS][COLS] = {
// Connect keypad ROW0, ROW1, ROW2 and ROW3 to these Arduino pins. 
byte rowPins[ROWS] = { 5, 4, 3, 2 };
// Connect keypad COL0, COL1 and COL2 to these Arduino pins. 
byte colPins[COLS] = { 8, 7, 6, 9 };
// Create the Keypad
Keypad keypad = Keypad( makeKeymap(keys), rowPins, colPins, ROWS, COLS );
void setup(){ 
 myservo.attach(12); //servo on digital pin 9 //servo
keypad.addEventListener(keypadEvent); //add an event listener for this keypad 
void loop(){ 
  //take care of some special events
void keypadEvent(KeypadEvent eKey){
 switch (keypad.getState()){
 case PRESSED:
Serial.print("Enter: ");
switch (eKey){
 case 'A': checkPassword();delay(1); break;          
case 'B': password.reset(); delay(1); break;           
default: password.append(eKey); delay(1); 
void checkPassword(){ 
if (password.evaluate()){
  //if password is right open box
 //Add code to run if it works
delay(500); //wait 5 seconds
//if passwords wrong keep box locked
 //add code to run if it did not work
   delay(500); //wait 5 seconds     

Step 5: Connection

keypad to arduino connection (refer image)

8 to Digital 5 of Arduino

7 to Digital 4

6 to Digital 3

5 to Digital 2

4 to Digital 8

3 to Digital 7

2 to Digital 6

1 to Digital 9

Servo Moter to Arduino connection (refer image)

Orange to Digital 12

Brown to GND

Red to 5V

Step 6: Set Up Locking Mechanism Inside Compartment

To lock the Compartment, I am using a three eye screws and a locking pin. Two eye screws are mounted to the inside of the front panel of the box. A third eye screw is mounted to the inside of the lid of the box. When the lid is closed, the holes of the eye screws line up. The box is locked by inserting a pin through all three holes while the box is closed. The box is unlocked by removing the pin.

The pin is a simple piece of steel wire (straightened paperclip). It is moved by the servo. The wire is attached to the servo at one of the holes on the servo horn (actuator arm).

Step 7: Mount the Rest of the Components to Over the Book

Attach compartment to book spine.

stick keypad on cover of book.

Step 8: Covering the Book With New Cover

to hide the compartment and keypad you should cover it with paper or something which can give the book a vintage look.

After covering the book , name the book such that some letter of name are on the top of your password (number).

letters should also cover keypad's button ( A & B)


In my case

password is 14471


number 1,4,7 of the keypad are under letter A, 0, 1 initiated on the book

So when i will press A001A , my door of the safe will get unlocked

Make a cut on the spine of the book where the door of the compartment is. So it can get open.

note: you should cut this very neatly.

Step 9: YOUR Secret Book Is Ready

Safety Challenge

Participated in the
Safety Challenge

Epilog Contest VII

Participated in the
Epilog Contest VII



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    3 years ago

    WOW! Impressive!