This is to use your XCarve as a plotter. This will only work with the spindle exposed. This is meant for the CNC4Newbie z axis and spindle mount. You will need to use M3 bolt and nut to hold the retainer on. You can use M3 or M4 bolt and nut for the spindle clamps. There is a spring on top of the ink cartridge inside of the tub so there is constant pressure on the ink cartridge pushing down onto your work. This was designed around using a Schmidt 888 pen cartridge.
https://www.exoticblanks.com/schmidt-888-rollerball-refills-blue-choose-width.html