Update, changed wall thickness of spool half to 1mm. It was unnecessarily thick at 2mm. I can add a 2mm version if requested.
Update, added rafts to pieces that have small buildplate footprint. This should help prevent piece from lifting off during print.
Instructions
Hack a common everyday pen into a usefull tool!
Remove all parts from Pen, save tube.
Print parts, all together at once is best --a. Tip (1 or 3 mm or both) --b. Spool Holder --c. (2) spool half. The spool can be glued together, this makes for a better print in my opinion.
Use a heat gun to soften plastic pen tube in order to insert printed parts.