This model is what I designed to help me calibrate the steps/mm and alignment of my printer. I found that the error on a standard 25mm cube was greater than I liked, and I'd often forget how it was aligned, so I wouldn't know if the corrrections applied to the X axis or the Y axis.
This model is 100mm in each direction, and has axis markings on each arm.
calibration_axis.STL | 7.2KB |