In this article are the methods that I have used many times in making secret hollow books. I have made these Secret Books in many different ways, depending on the application. You will need a ruler, a pencil, glue, a razor knife, a 1/2 inch paint brush, 2 small pieces of thin cardboard, and a book.
The first thing to do, when making a secret hollow book, is decide what is to be placed in it. From there you can choose the size and cover of the secret book. A good thing to keep in mind when choosing the book, is where you are going to keep it. Staying with the same type of books that you would normally have is always the best bet.
Just for an example, it is a small flask that is to be hidden. The first thing to do would be to measure its height, length, and width. With these measurements it will be easier to select your secret book. Let us say that the flask is 6 inches tall, 4 inches wide, and 1 inch thick. For my Secret Hollow Book I chose a hard cover that was 8 1/2 inches tall, 7 inches wide, and 2 1/2 inches thick.
The next step is measurements. With my project I measured 7/8 of an inch up from the inside of the back cover of the book. this is the center point. Open the book at that point, and make a mark 1/2 inch in from the outer edge of the pages. draw a line from top to bottom, and down the outer edges of the pages. Now do the same from the spine of the book. these lines mark the sides of the secret hollow. Measure down from the top of the book 1 1/4 inch, then do the same from the bottom. Now draw the lines on the page to make the box. This will be your cutting stencil. Next, measure down from the open page 1/2 inch, and slide 1 of the thin pieces of cardboard between the pages. Then measure 3/8 of an inch from the outer 3 edges, and draw your lines down the outside edges of the pages. This is the glue border. This will allow for some movement of the pages, this helps prevent damage to the Secret Book, and detection. Now, cut out the Secret Hollow, making sure not to cut past the cardboard. Once the cutting is done, remove the cardboard.
Glue the pages together. Use the paint brush to spread the glue very lightly on each page, and back cover, staying inside the glue borders. Now follow these steps on the front half of the book. Once the glue dries, your Secret Hollow Book is finished.