By now most of us have seen how to hollow out a book to make a hidden box for storage. If you need instructions on how to hollow out a book there are many instructables to choose from, so this instructable will assume you've already made a hollowed out book safe and focus on how to make a semi-hidden latch to keep prying eyes out of your stuff! Obviously any latch used on a book safe can be overcome with a prying tool, but having a latch will deter the curious from looking inside.

Step 1: The Plan....

The latch for this book safe is made from 7 components:

a 3/32 steel rod
a short piece of aluminum tubing
a small spring
a short 2-56 thread screw
two pieces of thin flat steel

The crude drawing in the 1st photo shows the general idea. The 3/32 steel rod sticks out slightly from a hollowed out part of the bottom of the book, and pushing this inward moves the bent piece of the rod that extends into the cavity of the book.

The 2nd photo shows the bent 3/32 rod and the short piece of aluminum tubing. The 3rd photo shows the placement of the 2-56 screw. I drilled and threaded a hole in the aluminum tubing for this screw. The 4th photo shows the placement of the spring.

When the rod is pushed from the bottom of the book, the bent portion will disengage from the mating piece shown in the next step, and releasing the rod allows the bent portion to return to the mating piece. If this seems confusing, don't worry -- this will all make sense in a subsequent step.

Step 2: Hollow Out for Installing the Lock

Lay the completed parts from the previous step onto the border of your previously hollowed out book, and remove enough material to recess these parts. Also, remove material for the two pieces of thin steel, which will be used to hold the locking mechanism in place. Be sure to place this locking mechanism so the bent portion of the 3/32 steel sticks out about a half inch into the book cavity. In the next step you will see how this comes together.

After you've hollowed out where the mechanism will go, cut a small indention where the 3/32 rod sticks out the bottom. This allows for the rod to be slightly recessed (2nd photo).

Step 3: Making the Rest of the Lock

Mount the movable portion of the lock (the part you just made) into the hollowed out portion of the book safe. I mounted mine in a bed of epoxy, then attached the metal plates to reinforce it.

The other portion of the lock is shown in the 1st photo. This piece will be mounted inside of the front cover. I made mine out of a piece of scrap hardware in my junk box. The slot cut in this piece is where the bent portion of the 3/32 rod will mate (see the 2nd photo).

Step 4: Mount the Remainder of the Lock

Figuring out placement of this piece of the lock is sort of a trial and error process, since it's difficult to figure it out after the book cover is shut. What I did was measure carefully where it looked like it should be placed, then I temporarily taped it inside the front cover to check the make sure the latching mechanism would engage. Once I found the exact placement, I attached it with some industrial epoxy. I could have bolted it in, but I didn't want the bolt heads to show on the outside of the front cover.