Z-Alingment tool

Dual Z-axis alignment tool.
See pictures for placement

Make sure that the blocks are placed in front of the belt of the X-carriage. (in the first half of the extrusion)
The belt can not be under the tool

How I use this:

Place the blocks. Lower the Z-axis. (I use live movement). When 1 side is (soft) touching then this will be the height you use for the other side.
Disable stepper motors.
turn the coupler on the side you want to lower.
Check if both sides have the same pinch feeling.

enable stepper motors. remove the blocks home all axis. (depends on how your printer works and how the motors get activated again - for safety you can remove the blocks first but then you have the chance the Z alignment will be off again). I've installed anti-backlash nuts on both sides for that reason.
If for some reason the alignment is off again after a very short period then you will need to check the eccentric nuts on both sides of the Z-axis.

Print instructions:

Material PLA
Use 15% infill to give the blocks some sturdiness.
Higher resolution will give better results

Post-processing: measure with a caliper both blocks and try to make them exactly the same size. (elephant foot can throw the measurement off)