To use CNC free software, apply the G-Code to the specific pattern you want the CNC machine to create. Writing a simple G-Code by hand is ideal for lines or circles, but there are some CAD or CAM programs that make more complicated systems easier to create. Design the desired outcome on a blueprint first, and then transfer the pattern to the machine with the appropriate codes and coordinates.
Some G-Coding tools include GCodeTools for Inkscape, which is a free program that helps users generate art on the Inkscape interface. It is one of the most versatile free options, though it may seem limited compared to other software systems. Other programs include ESTLCam, which costs money to use but also features a user-friendly interface and a 2-D environment on which users can draw programmable parts.
Other, more expensive CAM programs include CAMBam, which comes with a free trial period and allows users to get accustomed to the interface before purchasing the program itself. Additionally, users can invest in MeshCam, which is one of the most expensive CAM program options but also one of the most versatile and comfortable to use, according to Hack a Day. This program is geared toward 3-D more than 2-D, which means that there is a learning curve for beginning users.