Summary This is for fine tuning the alignment of my dual extruder. I got tired of measuring boxes. This prints much faster, and is easy to adjust. It is configured for .4 mm nozzles. Two lines .8 mm wide intersecting, and each color is 1 mm high. With two colors, it is fairly easy to tell which way the alignment needs to be adjusted, and you can make the final adjustments just by looking at it. When you have everything aligned, the thickness should be right at .8 mm. Print with no ooz shield or wipe and prime tower. The left end of the cross may be a bit globby as the extruder may drool a bit, but the right and back sides will accurately demonstrate the quality of alignment. If one end of the cross is certain to be messed up, you will always know which way to orient it when examining the result. On mine, the initial starting point of each layer is fatter then the rest of the layer. This is actually a good thing. It is amazing what he last few hundredths of a mm will do for the appearance of the entire model. Instructions Print it in two colors and look at it. In Cura -- load upper and lower, right click and choose dual extrusion merge. Now load one color. Print. As this was designed for a .4mm nozzle, you can scale it proportionally to be suitable for any size hot end. ie: If you have a .5 mm nozzle, scale it to 1.25 or 125%. If you have a .3mm hot end, scale it to .75 or 75%. Measure the thickness of the lines in the one color version, and subtract from the thickness of the parallel lines in the two color version. Divide the difference by two, and you will have a precise measure of the offset yet to make. You can see from the color alignment which way the offset should be adjusted. If the bottom layer is mashed down too far onto the printing platform, it will be naturally wider. Adjust your calipers to avoid including measurement of the bottom layer. You can print a dual extrusion merge on the upper and lower pieces, and add the one color piece and print the entire calibration in one job.