It is proof of concept of smallest possible and simple fountain pen with piston mechanism.
To use OpenScad you also will need threads.scad library
...Plus (http://dkprojects.net/openscad-threads/). Pen size and some features (for example cup thread position) can be changed.
Most recent sources can be found here https://github.com/sanja-byelkin/SimplePistonPen
To make the pen default configuration additionally required:
1. Nib #6 (it is nib size standard, can be used any nib (Peter Bock, Jowo, Noodler's, Jinhao, or even antique nib from some old broken pen))
2. Ebonite feeder for Noodler's ahab/konrad pen or selfmade ebonite feeder with diameter 6.3mm.
3. Two o-rings for piston (mine goes from some set of o-rings marked 2/3" - 1/2" bought in plumbers part of supermarket, see photo, external diameter of them is about 9mm, inner about 5mm, ring is about 2mm thick).
4. a bit of silicone grease
5. Sand paper or something else to polish inside tube with diameter 9mm (I used sand-paper 400, 800 and 1500 and put is with super-glue on printed cylinder which put on BBQ-steak).
