Here is a way to send secret messages to your friends.
Trace exact duplicates of the cipher sender for your friends, and assign each one a different three-letter code name.
Send messages on strips of tracing paper the exact width of the alphabet area on cipher sender.
To write the message, position your tracing paper strip over the cipher sender. Mark a short line at the left edge arrow above the A. Over each letter in the desired word, mark a number on the tracing paper in its proper sequence. Example: for the word box, write 1 over B, 2 Over O, and 3 over X on tracing paper laid over the cipher sender.
Draw another short line on the left edge of the paper directly under the completed word.
Move the paper up so the line under the first word is on the line (top arrow) above the A.
Complete the message word by word.
Put a cross instead of a line under the last word.
Give your code name after the last word.
To read the message you receive, lay the tracing paper strip over your sender with the first line at the top left at the arrow. Write the letters found under the numbers in sequence—1, 2, 3, 4, 5, and so on.
Can you read the sample message shown here? Copy it on a piece of tracing paper. Then lay the tracing paper message over the cipher sender, and read the letters in number sequence.