When using split-core Hall effect current sensors, they usually need to be calibrated (zero and gain). This calibration stand allows you to have 4 positions with various currents that the sensor can be clamped on to.

The full explanation on how to build and use this can be found in this article on EDN:
https://www.edn.com/hall-effect-split-core-current-sensor-calibration-station/

Creality

Ender 3

Doesn't Matter

Yes

0.2mm

20%