This file was originally created with a wooden tablet in mind, but it can be used to engrave a variety of surfaces. The Pigpen cipher—also known as the Masonic cipher, Freemason's cipher, or tic-tac-toe cipher—is a simple substitution cipher that replaces letters with geometric symbols. There are multiple variations of the cipher, but the one shown here is the most commonly used. Each section of the grid is called a "pen," and the dots within them are referred to as "pigs," which gives the cipher its distinctive name: Pigpen.

This cipher has been used for centuries and remains popular in puzzle games, escape rooms, and other recreational cryptography activities.