Hollow Book, Invisible ink, Black light

In the family gift exchange I got my 13 year old brother, who is really into spy stuff.  In thinking of what I could make him I came across an instructable for a hollowed out book.  I had done it before and it worked really well, so the first inspiration for this gift was:
http://www.instructables.com/id/secret-book/

In addition to the book I thought it would be cool to put something inside that was spy related: fake passports, finger print dust, etc.  I settled on some kind of invisible ink and a writing utensil.  After some investigation, some trial and error, and some inspiration from:
http://www.instructables.com/id/25-Cent-Invisible-InkPen-UV-light-visible/

The following is the steps it took to build a spy hollowed book, with a ordinary (in appearance) highlighter, and a black light to reveal the secret information.

Step 1 Gather the Materials

I spent $10 on the gift, when all was said and done.

Materials:
Book ($1-$3)- Any book from a thrift store which is hardback and has a sturdy spine will do.
Glass candle ($1)- At Wal-Mart for 1 dollar
Black light ($5)- I chose an LED black light on Amazon.
Highlighter- An old highlighter I had lying around.
Felt ($1)- I used one sheet from Wal-Mart
Elmers Glue- I had some at home, but you can find a little thing of it at Wal-Mart for a buck.

Tools:
Paint Brush
Razor Blade
small pan
metal bowl
scissors
containers for ink mixing

Comments

[nomooremr.niceguy]

Were I to boil the diluted highlighter mixture, would it show up better when made to fluoresce?

[justjude]

This is a fun idea - I think it would be fun for a cub scouts project. One of their requirements is writing in secret code and every boy likes to have a secret hiding place!

[Browncoat]

I've been trying to do a book & been struggling a bit. Of course! Glue the pages FIRST!!! Thank you!

[scoochmaroo]

Fantastic! What a great present.

[mmarrington]

Thank you!