UPDATE: My new pen design is here https://www.thingiverse.com/thing:1460520

This triangular pen body accepts a Bic pen ink stick and has customizable text on 3 sides. It has a small slit so you can see how much ink is remaining.

I print with Low quality settings and a raft on a Makerbot Replicator 2, and the print takes about 30 minutes. Change the filament color at about 30% for high contrast on the front face text.