9/24/18: The test pattern should now fill most of the bed, 205x245. I could have gone 209x249, but this way the test pattern stays in nice 5mm widths. Keep in mind that Cura has a bug where if you try to slice a 0.1 mm thick part and your first layer height setting is 0.2 mm, then it will slice a blank file that does nothing instead of giving you a warning.

Also be warned that you can damage your stock PEI bed fairly easily. Be careful with this one, it could create a mess that is difficult to get off. Based on initial prints this is turning into more of a torture test for my MK3.

9/20/18 Update: Little did I realize that Cura will not let you print a 210x250 area unless you manually change your stock printer specs. Even using PrusaControl, it just froze. I bumped down the width to 205x245. I figured that would be easier to use for everyone.

This will need some tweaking it's not even close to filling the whole bed. Will make it 245 wide. But there will be a clear and evident 5 mm gap on two sides.

Was looking for something to clean my bed, and figured this is dual purpose, calibration test and cleaning. Including various thicknesses from .1 mm through .5 mm for those are sensitive to the amount of material being used.