50, 100, 110 XYZ Calibration Ruler Minimal

I was wanting a minimal 100 mm relatively fast test to calibrate steps without all the other tests that other rulers on thingiverse have in them. I came up with this. I put the marks on the Z axis on the inside so that digital calipers can get to the marks without anything being in the way. When measuring, measure center to center of the marks or top of mark to top of mark. You can adjust for the outside wall printed line being slightly thicker (because it has nothing pushing against the outs