Prusa mk3 bed level / first layer test file

It seems like a lot of folks on reddit have questions about getting their first layer height properly calibrated. A big part of the problem I think is that the prusa first layer file only has one little square at one location.

So I made this larger version that has nine squares, spaced across the important corners. I've included prebuilt gcode for PLA and PETG.

This file helps for two reasons:

* It gives you lots of time per print to dial in you "live z adjustment" - just turn the knob as it is printing and you can see each of the squares get better (or worse)

* It tests the full area of the print bed - this is useful to let you perform your second (somewhat optional but really good if you want to get a great first layer on bigger models) "bed level calibration" tweaking the offsets for left, right etc...

I recommend as it lays down the single line around the bed that you watch how that line is sticking in the corners, if it is pulling up you probably need to lower li