I decided to just come up with a calibration method without even reading up on what others have done. I'm sure this is idiotic, but there you go. Enter some starting values for cubes 1 through 4 and also the extrusion width you plan to use from your slicer. Then enter your measured values into the Google Sheets doc: https://docs.google.com/spreadsheet/ccc?key=0AlgQOeq77lH0dHc5cTl3alUxTm14ODQ5M0RYblhUd2c&usp=sharing And tweak the x, y, z and e calibration factors to try to come to the lowest overall difference values. And please let me know how idiotic this method is.