Use your CNC router as a plotter!
This was inspired by TadasM https://www.thingiverse.com/thing:1847711
However I wanted to make it easy and cleanly printable without any supports, imperial instead of metric and working with sharpie so I created my very own version from scratch in Fusion 3D. I love the concept where the spring is incorporated in the design! (And it works!)
This uses 1/4" 4" screw from home depot that has only small thread length at the end - just cut out the thread and you have a perfect 1/4" shaft of 3 1/4 length for this project.
All other screws are 8-32 - the class 2b threads are perfectly realized in the stl, no need to retap.
All dimensions are very precisely set in the file; the top collar fits very very tightly and stays even without the screw and the bottom collars slide freely but without any play on the shaft. The screw holes all have 8-32 thread realized and manually adjusted for exact fit.
The hole fits the standard sharpie and the double sided sharpies.
I'll post more pics of it actually working on the CNC.
Prints without support. I used 3 outline shells for extra rigidity and 4 top and bottom full layers. Printed in white PLA+ which does have feel of UHMW. Try it - it is very durable and beats normal PLA, ABS or nylon imho.. If you are not sure your printer can make the big sharpie hole without support, stick some in the middle. (but most well tuned printers should be fine)
Orientation is how you see it here, this ensures the perfect realization of 8-32 threads which are in 2b class and the screw goes in and out perfectly.
It is great when you just design a thing and it prints and it is exactly as you wanted!