I love anything with secret compartments. From the big (secret passageways) to the small (a secret pocket in a jacket), there’s just something delightful about things that are hidden away.
Step 1: Equipment
-big book (looks better old and choose the size that most fits your needs)
-glue (mix flour and water)
Step 2: Preparation
Place a plastic bag over the front cover so that the glue won't stick later.
Now glue down the sides of the pages with glue an put it somewhere it will stay in place for example a vice or just under some bottles of water for at least 2 hours to make it hold. If it hasn't held repeat the process.
You can now take of the plastic bag and cut into it as deep as you require.
If afterwards the glue isn't working glue it again ,you can also sand it in the middle
Step 5: Filling
You can fit whatever you want in it from passports to money to security codes what ever you like