Yet another calibration thing.

The regular calibration cubes may not be the best thing to calibrate a printer. Edges and particularly the bottoms can be distorted. If you measure the overall size this can yield a slightly inaccurate measure of scale.
This thing has lines and diamonds on both horizontal and vertical faces at 25mm spacing.

I have uploaded 3 variants of this thing. The complete corner will give a little bit more information but the choice is yours.

I have other test patterns here -
http://www.thingiv