print largest square possible on your printer.
you may leave center empty.
on one side leave marking point (that will allow you to understand your axes)
make it 10 mm height
i use different figure (see below)
once you print it, measure X and Y sizes. calculate difference and scale factors as mentioned in post above
put adjustments in config.g with M579.
reboot. enjoy.
36f9497a-37ef-43c0-a3b4-0f78c2252b37-изображение.png