This is a really clever design - its works great.
I printed a variation to fit on my homemade budget CNC and had it trace out templates I needed to cut out of thin plastic.
It took 2 hrs to draw everything, but worked flawlessly and was very accurate (no excess wobble in the holder).
I used eSun PLA+ and had no issues with flex. I had the pen move down 1mm from the surface of the bed to draw.
Well done and thank you!