This is a simple test for calibrating flow parameters. the cube dimensions are 1.000" x 1.000" x 0.020" thick (dimensions are in imperial aka inches).

use a brim to help bond to plate. orientate it with the opening on the top and bottom,

z height is irrelevant and you can neg z down 1/2 the height just to save time. the calibration formula I found on YouTube,

Desired wall thickness / Measured wall thickness then multiply the extrusion multiplier = the new flow number.

their example is 0.48 / 0.52 * 100 = 92.3 (rounded up to 93)

In my case... my example would be (desired wall thickness 0.020) 0.020 / 0.023 (actual) * 100 = 87 new flow setting