Infill & calibration square 40 mm X 0,4 mm

Test square to adjust layer heigth & infill between closed up lines.
If the infill line is higher then the neigbour lines, raise the nozzle slightly untill the infill is flat.
If you have Live Z adjust enabled on Marlin firmware check for how the layer is printed by changing the layer height. Good quality and first layer bonding is quickly observed and changed on the go.

Designed for 0.4 mm nozzle and 0.2 mm layer heigth.