Anti-roll hex body, functional pocket clip, 130mm length perfect for shirt pocket, secure cap.
I printed in PETG. No supports, around 20% infill. The “grip” component does require a +/- 8mm brim and must be printed tip down as shown, don't use a brim on anything else. I experimented with 0.1 to 0.15mm layer heights. 0.1 up to 0.2mm may work.
Please note: I had to use a tap and die (M9 x 1.25) to clean up the threads and a ¼" drill bit to clean up the inner diameter in the “grip” component so that the G2 cartridge would fit through easily. My modeled dimensions looked okay, so I feel this is more my printer setup than a flaw with the model, but I will keep working on it. Take your time and don't force the threads together as something will shear off and don't force the ink cartridge in as you can easily pull out the tip and get an ink spill.
The author hasn't provided the model origin yet.