I like to level my bed on the fly as posted here: https://youtu.be/4J2vn4V7Ygc In order to do so, I've created this simple model to help me test my bed while I level it.

To make things easier try to print you some of these: Anet A8 Hotbed Spring Bushing : https://www.thingiverse.com/thing:2146448 Wing Nut bed level screw knob for Anet A8: https://www.thingiverse.com/thing:2000216

Note: The bigger circle's diameter is 180mm.