Originally Posted by
CalG
I recently ran across an reference to certain Staedtler pens that readily clip into slightly modified plastic pen cases. Though I don't seem to find the on line reference at the moment, It had to do with producing PCBs, and using the ink as etch resist.
Myself, I refill the fiber tips for general output, a search for HP Plotter pens will find many vendors.
At the moment, I am working on the Kohinoor nib holders that use the smallish (about 2inch long) ink cartridges. These are ideal for fine work with the "rapid -O-graph" look.
I have a 7550a with the same pens
Hypo needles work well for refilling plastic cartridges without disassembly