GeirS' first layer calibration

I have recently updated my Marlin FW to support Mesh Bed Leveling. I got some hints on how to set custom GCode etc. in https://www.youtube.com/watch?v=mAU7cIZ0Hns. However the test print TeachingTech used, was only available to his Patreons - thus I quickly created my own using FreeCAD.