This is a pen plotter attachment for the Ender 3 Max by creality. It uses 2 M3x8 screws to mount into the attachment slot that was intended for your ABL sensor. It can be left permanently attached to your printer, even when not in use, since it clears the belt tensioner screws.
It holds two edding markers: a 3000 series for 1.5mmm thick bulk marking, and a 8400 for 0.5mm precision marking. Gravity alone provides the pressure for marking. Edding pens offer good ink quality and availability, but if you need something different, source files are included. Siemens NX12 .prt files are the original, anything else is an export, and may not reflect parametric design accurately, use at your discretion. ->remember to flip your coated bed to the uncoated side, since alcohol is necessary to remove any permanent marker that soaked through, but will also damage the coating.<-
Software wise, follow this tutorial: https://www.youtube.com/watch?v=CuWZWAfBsm8; but "G1 Z7 F10000" on command, "G1 Z8.5 F10000" off command, 6000mm/min speed for the 3000 marker OR 1000mm/min speed for the 8400 and offsets of -55mm X for the 8400 OR -71mm X for the 3400; and 3mm Y offset for both. note that the negative offsets may generate gcode that tries to move the head out of bounds. always double check your GCode in cura before sending it off to be drawn.
dragon drawn in my test images is "dragon head" by "el-grimlock" from deviantart, used under fair use. all files provided are licensed under CC-BY-SA.