I noticed a little wobbling in my printing, so I started searching for a solution.
I found the double cardanic joint by BoilerPlateDan, https://www.thingiverse.com/thing:42550, but it was simply too big for my Anycubic I3 mega, so I resized it a bit and made various modifications.
Like him, I decided to share the solidwork files.
After a little post-printing work, I found that my solutions works beautifully, reducing pratically to zero the wobbling. I decide to make a small hole in the 5mm End and add a small screw to better grab the axis of the motor. You can see it in the photo with the long screws (I used some old screws that I trimmed to the right lenght).
In the last photo you can see the calibration cube before and after the hack: in the left one the wobbling is visible, even if barely.
Better to print the two ends together, and maybe add a little space between the two, to let them cool especially while printing the points