This is a puzzle you can make on your friends and family. It's like that Sherlock episode where they use book ciphers to hide a message.
So you will need:
1. A book (preferably old).
2. A page to write on.
3. A fancible pen.
4. A place to write what you're going to do and how.
5. A reward.
Step 1: (Old) Book
You will need a book or some kind of text that you can use a cipher.
I picked up this book for 0.2 pounds at a flea market (there were lots of books like this one)
It doesn't matter really what text you use, as long as it contains a basic vocabulary of words.
The book i used had a lot of egyptian names and stuff so i decided to make the code include some of them.