As i love EDC (Every Day Carry) and especially Fountain Pens, i was seeking for a decent Pocket Pen.
Found the (full sized) Design by Dinis, tired it… and started to modify/edit his design.
Shorter, longer Cap to have some Room above the Nib. Reworked the Threads.
The Cap is meant to be posted while writing - and it posts very secure and snuggly.

So, here's my Remix: 
a Pocket Pen with a decent Nib Unit, even smaller than a Kaweco Sport.
Fits one standard international Ink cartridge.

FDM Printers: Print the body and cap at 0.12mm layer height and the section at 0.08mm
 - tried PETG and PLA myself. Fuzzy skin might work, but i prefer clean contures.

SLA/MSLA:  works as well, tried it with a friends Elegoo Mars 3 Pro. Just make sure to orient correctly to prevent a vacuum.

The nib units are Bock 250 or #6, and they can thread right into the section but depending on the printer calibration you might need a bit of effort, if that doesn't work you can scale all the parts by a little bit and that makes it easier to fit