Good progress were made over the weekend:

After replacing the Arduino it simply worked. Below is an engraving test for Muffin, our hamster, who is absolutely thrilled about this new sign as you can see.

I did further tests with harder material such as acrylic but clearly the Z axis shows its limit and there was too much bending. I will replace that one with something stronger.

The next steps are also to tidy up everything and put the power supplies and the controller in an enclosure