Concealing objects in a book

There are many real and fictitious occurrences of concealing objects in a book. Items can be concealed in books in a number of ways. Small items such as a photograph or a note can be hidden in between the pages of the book. Thicker items can be hidden by removing the interior portion of some or all of the pages, creating a book safe or hollowed-out book. Book safes are easy for their owners to recognise, but they do not stand out to a thief or other intruder.
Another type of concealment is the hiding of messages in the text or on a book's pages by printing in code – a form of steganography. For example, letters could be underlined on sequential pages, with the letters spelling out a message or code. There are a number of actual and fictional examples of items or messages having been concealed in a book.
Illicit chemicals may be smuggled by soaking individual pages with them.
Books are used as a concealment device in part because they are readily available and inconspicuous in many settings.
Methods of concealment.
Hollow book safes.
Prices can vary based on the cost of materials, additional features, and resources used to create the functionality and aesthetics of the hollow book. The main functional purpose aims for the containment of valuables, memorable items, or contraband within the cloak of an ordinary book. Thus maintaining privacy and security from unwanted intrusions and/or theft.
The scale of gadgetry used to create the seal of a hollow book's closing properties have ranged from simple to complex. Simple elastic bands, interlocking rope, and other common book closing techniques are used. Other times, hidden magnets do the task as well as the unusual use of complex locking mechanisms that require a lock and key combinations have also been used to keep a book closed.
Material choices used in the creation of the hollow book's body are usually actual books. However, other plastic, metal, cardboard, or paper materials have also been used to either simulate a real book, or to be used as extra features.
Many book safes are handmade. Structures made from real books are sealed and pressed before hollowing the inside pages with a sharp cutting utility. Sealing the back and allowing the front cover to act as a door that can be opened and shut. While other hollow books are made from cardboard cigar boxes, simulating a book on the outside.
Steganography and hidden messages.
Messages can be hidden within a book using steganographic techniques. Invisible ink may be used to write words and sentences in the book, or by underlining certain words or letters a message can be crafted.
The author of a book may include coded messages by carefully choosing the wording, such as in a simple acrostic where the first letter of each word spells another word. There have been many claims of a Bible code, alleging that God secretly placed hidden messages in the Torah, and that these can be discovered by suitable manipulations of the text. The 1997 book "The Bible Code" by Michael Drosnin is one of the most famous examples. On the other hand, it has been shown one may discover "hidden messages" in any book using this method.
Choice of book.
In fictional uses of book safes, the title or subject of the book can be symbolic or related to the nature of the object, e.g., hidden money in a copy of "The Wealth of Nations". There are a number of cases from films and television series where an item is hidden in the Bible.