Cheap 'N Cheerful: Make your own : Secret hollow book

This tutorial has been taken from W ikihow

View the full tutorial at Wikihow's secret hollow book page

A hollow book can be a nifty way to hide something, whether it's a spare key, a secret note, or even money. Most people wouldn't think to browse your library for private or personal things. It's also a great way to pass something to someone discreetly--an unsuspecting onlooker will just think you're sharing a very good read!

Select a book, preferably a thick one with a sturdy hard cover.
Select the first few or as many pages as you want and hold them to the front cover with plastic food wrap so they do not get messed up with the glue. These, except for the last one of these pages, will not be cut out. This will allow the book to look like a book when it is opened up and will cover the hole itself. The page nearest the hole will be glued later on and explained in the last step.
Mix a solution of white glue and water. Make the consistency just enough for the glue to be runny, and absorbed by the edge of the book's pages. 50% to 70% glue (30% to 50% water) or half a 35mm film canister full usually works well, but use your judgement given the thickness and size of the book. Alternatively, try a craft glue like Mod Podge.
Hold together all the pages after the one you set aside earlier and brush the edges with the glue solution so that it is reasonably absorbed. This will hold them together. Remember: Clean the brush off immediately, or else it will harden and become useless.
Let the book dry for fifteen to thirty minutes. Place a sheet of plastic food wrap in between the glued pages and the page(s) (if any) that will not be cut (including at least the previously selected page and the front cover) so that they do not touch and stick together. Place something heavy on top of the front cover so as to apply pressure.
Open the book to reveal the first glued page. Draw a half-inch (1.2 cm) border within the edge, on all four sides (including the spine).
Cut along the inside of the drawn line with a straight edge knife (a box cutter works especially well). Try to make the cut as vertical as possible, or else try to tilt it so the hole will narrow as you go down. Using a ruler, as shown in the image, can help a lot. Apply enough pressure to cut a few pages at a time.
Continue cutting through the layers. Do not rush this step, because the slower and more carefully you do this, the smoother and straighter the inside edges will be. Remove the bits of paper from the inside that accumulate from the cutting.
Brush the glue solution onto the inside edges of the hole and allow it to soak in. The glue dries clear, so if it drips a little, do not be concerned. While waiting, apply a second coat of glue to the outside edges of the pages.
Brush the "frame" of the hole with a light coat of glue. The saved page will be glued directly on top of the hole, essentially covering it (for now).
Close the book again, this time without any spacers. Allow it to dry for about 15-30 minutes. In this drying phase, the saved page will become affixed to the hole, as mentioned in the previous step.
Cut the saved page along the edges of the hole so that the hole is visible and accessible once again. The insides of the book may still be moist because the book had been closed while drying. Now is a good time to let the book dry while it's open.
Check to make sure every part of the book is thoroughly dry. Touch it with your fingers, and when you are certain it is dry, fill it with your treasured items, shut the book, and put it in the bookshelf. Only you will know that this book has a compartment because it will be surrounded by many other books!