I just made this simple flow test cube for obvious purposes. The fillet is present to prevent the bulges on the corners to give a wrong result.

Before doing this test, measure the diameter of your filament in various spots and use that value in the slicer for the filament. Doing so, all filaments of the same material will give a close or equal flow value. Then calibrate your extruder Esteps, which depend on your motor and extruder parts

After your flow is calibrated, you can print with 2 or 3 perimeters and no gap filling to verify the perimeters do overlap.

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