I have always wanted to make a hidden book box, and it seemed fitting to make a TARDIS version for my boyfriend because he loves Doctor Who.
Follow these steps to have a hiding place that is bigger on the inside.
I used an old book I got for free from my school's discarded book fair. The blue color was close enough to the TARDIS. Try to choose one that is deep enough for your desired box.
Firstly, glue the last page to the back cover. I also glued every 20 or so pages together just on the edges.
Mark off the area of the box size you want with a ruler.
Use an XACTO knife or similar tool to cut the pages. This will take quite awhile, depending on the depth. Remember to leave a few pages at the bottom.
My cuts were not very even. It may help to go slower or remark the edges each time you cut a chunk.
Next, mix glue and water to coat the outside and inside edges with a brush. It is best to put something heavy on top of the closed book to help the pages stick together. Leave sit for awhile until they no longer come apart.
After this was done, I chose a quote from Doctor Who to write inside. You can also paste paper or a design to cover the book's text (however, I thought the words on that particular page were appropriate for my situation).
For the TARDIS cover, use a ruler to mark (in pencil) the design. This involves a lot of trial and error (using a picture for reference). When happy with the dimensions, trace over the lines with a permanent marker.
For the white parts of the design, use painter's tape to make clean edges while painting with white nail polish. For the words, I dipped a tack in the polish and slowly formed the letters.
Note: Acrylic paint would not stick to the cover material for me.
Use a permanent marker to do the note and ambulance badge (using a picture for reference). After the final touches, the TARDIS book box is complete!