PRINT 6 WALL LOOPS AND 50% FILL. MAKE EXTRA STRONG 

ONLY WORKS if you have a AUTO LEVEL System on your printer

start with the wire holder and print a few spacer…you can adjust height in slicer. print these at 0.20 if you adjust size make sure to adjust the layers by 0.20 once you know the spacer required for that corner of bed, print one that size without spacers.. if you can print ABS is best 

1) if you have a open source printer, best to create your own firmware, if not it most printers you can just buy the old style screen and write your own firmware, i have upgraded all my in house printer to open source, kit are out there even for the Ender6 and Ender7 Printers. for around 30 bucks, open source allows many more adjustments over touch screens.

2) recommend using the EZABL level sensor, it is much better than the BL or CR, would require making firmware. the sensor default is 5mm off bed, when you level you want to be between .29 or .3, you will see these numbers on screen doing auto bed level, use baby step and a piece of paper until it just barely touches, then print a large circle with a brim, the brim when correct will be solid not stringy, then print a test block 20mm square 10mm height and measure, from there you can tweak it, once you get a true print 10mm height you are spot on save all defaults, now just sit back and enjoy printing perfect prints.

it does take a little tweaking to get it perfect, but the time and effort is worth it. I have printers here that print 24/7 for a year i never touched them they just print. once done you will ask yourself why you didn't do this sooner.. it is a true game changer for your 3D printer