A pair of 200x200 shapes to test large area Z-cal, and more interestingly warping of the bed. Printed with as little squishing as you can still get adhesion, any low or high points will show as rough/smooth first layer once the print is cooled and removed.

With a MK42 bed on a I3 Mk2, I was seeing poor adhesion at the rear left of the cal2 test - the perimeter of hte bed was OK, but the middle seems slightly dished. To compensate, I set 'bed level correction' -ve at the back, and +ve at the front.