X,Y and Z axis 150mm calibration prints

Two calibrators for steps per mm calibration. They are this big (150mm) so that the calibration error resulting from wrong steps per mm is more measurable and errors stemming from other things, like wrong bed levelling or over/underextrusion are less pronounced, making the calibration more accurate. It is 150mm instead of full bed size (in common Prusa I3 clones and other printers with 220mm each way working area) to avoid hitting things like bed glass clamps and other accessories one might stic