Building the Ender 3D printer - attaching the z-axis motor
Create a 20mm X 20mm cube
Two of the sides will have your initials (one extruded 2mm and the other cut 2mm). Make sure the letters are bold and easy to see.
The other sides (including the base) are up to you but they all have to have something that will measure the print quality of your printer.
Callibration Cube in Prusa Slicer
Additive Manufacturing Certificate