It can be hard to talk about 3D printing to anyone who isn't familiar with the technology. Having something on your person that can help explain the whole printing process is helpful, as well as being a neat conversation piece. Sure, pens are super cheap and more or less utilitarian, but a 3D printed pen (let alone bolt action) is pretty neat in my opinion. Used it on my exams!

Feel free to print in whatever color plastic you want that matches your ink color! Just be sure to use filament with good layer adhesion (probably won't matter for the majority of people).

Side note the small hole in the body of the pen near the tip is to monitor how much ink the cartridge has. Once you no longer see ink through the hole, it's time to change your cartridge.