alt Hacker NewsA year or so ago I was setting up my small router table/mill and I mounted a Sharpie holder to it and made some line art. Quite slow due to the leadscrew pitch of the mill but it worked well [1].
Like the OP I used svg2gcode and others. The original pen holder I printed worked but I ended up modifying the design and adding a bronze bushing to hold alignment better and a mount for a microswitch so that the pen holder also functioned as a probe to set the Z position. [2]
In order to be able to change pens I made a little "half crosshair arrow" that I would run the gcode for on each pen change and verify the overlap was the same since it is difficult to align the pens exactly on change.
All of this was done using V2 Smoothieware as the firmware.
[1] https://youtu.be/nJI-yXbHHJA?si=F9bXftj7UEXyuRxa https://youtu.be/ZSP37Kgp7Tc?si=Mn_IKjU9t9zmaOml