Test object for compatibility with LEGO(r) Technic axles and '+' shaped axle-holes.It is tapered, so you can measure very precisely how your 3D printer handles the critical dimension of an object shaped like this.Print this out on your 3D printer. Try inserting both '+' shaped ends into a LEGO(r) element with a '+' shaped hole. Because this object is tapered, it will not go in all the way. Where it stops will depend on the precise details of how your 3D printer creates objects shaped like this. Use the results of your experiment to calibrate SCAD files that you use to create other objects.This is about 125 millimeters long (5 inches). The smaller version "axle-test-l60" is about half as long. If neither of these fit in your 3D printer's build volume, download "axle-test.scad" and use OpenSCAD to make a shorter one (find the line that says "length = 8.0 * lss;" and change 8.0 to something smaller).One end is aligned with the X axis and the other end is at an angle; depending on your 3D printer, one or the other might be better. Full instructions and further explanation are in the block comment of "axle-test.scad"