Finding no Australian calibration tools, I've remixed the US version for Australian users. The ring is 40mm in diameter, with a 23.60mm inner circle, exactly the size of an Australian 10c piece. There is a 3mm bump at the top to indicate direction. The ring is 2mm thick, the same thickness as a 10c piece. Print with solid infill for best results and read the guide here... http://blog.mcmelectronics.com/post/3D-printer-calibration