A free program, however I liked it enough to buy the Pro program. I used to play with other cad programs before including the King of all programs called Autocad. However, I'm not designing the Space Shuttle.
It's a lot of fun being able to design your project on the computer before building it. I'm in the process of learning the program, and have found that Youtube, and other support groups are awesome for this program.
Attached is a jpg export picture of a metal cabinet I'm building/welding to fit on top of my toolbox.