This object is designed to help you check that you are correctly leveling you printer bed. It prints three nested squares. Try to adjust your printer as the object prints (watch out for your fingers :) ). Keep adjusting the bed level until the lines are laid down evenly.Level your bed, print the object and check the results.You may want to download the scad file and adjust the x, y and z dimensions to match your printer bed.The default values are: X_MAX_LENGTH = 173; Y_MAX_LENGTH = 163; height = .3; border_width = 0.2; // This should be slightly less than your extruder widthIf your gcodes are empty or simply doesn't print try increasing the height and or the border_width.This is an updated version of the calibration tool as I've found this version easier to work with.See the calibration page on reprap.org for full details on calibrating your printer.http://reprap.org/wiki/Calibration#Bed_Leveling