Two calibration parts  One is a .5 mm thinwall part, the other is a 20 mm box.  There are sliced gcode files as well as the .stl files. To print the parts download the files to your computer.  Open your printer host (Printrun/Pronterface if you are building the Baja i3 kit) and open the .gcode file.  You will then be able to print that file.