There’s a long answer and a short answer to that question. The short answer is that by 3D printing fountain pens I am able to combine two of my hobbies: 3D printing and fountain pens!
The longer answer is, I hope, more interesting. By 3D printing my pens I am able to make a product that is beautiful, functional, and interesting.
I suppose that I might be able to achieve at least a coupe of those virtues when making fountain pens by other methods, in particular by turning acrylic or wood in a lathe. (I’d love to have a lathe…). However, I think that no matter how beautiful and functional a pen I could make that way it would be difficult for me to achieve ‘interesting’. After all, there are so many beautiful and functional fountain pens already available from large and small pen makers that my efforts would be largely superfluous.
What makes a 3D printed pen interesting?
Well, that depends on who we might be thinking about. Many people find 3D printing and 3D printed objects interesting simply because they don’t often see them. (I’ve been exploiting that by giving 3D printed gifts to friends and family. Please don’t tell them!) That probably counts here because very few fountain pens are 3D printed. If you are ‘into’ fountain pens then a 3D printed fountain pen is intersting, and if you are ‘into’ 3D printing then a fountain pen is an interesting thing to print.
There’s another important way that 3D printing allows the manufacture pens of more than usual interest: 3D printing allows the pens to be intricate in ways that are not easily (or cheaply) achieved with other manufacturing methods. Consider the surface texture of my Pattern 3 pens. Is that not interesting?

The layer by layer nature of the 3D printing process allows repeating spaces in the surfaces of varying depth and widths that give the surface an apparent depth and hand-feel that is unlike all others. Even completely the completely uniform layers of the grip sections get a peculiar sheen from the 3D printed layer lines.
Why 3D print fountain pens? Look at the results and you will see.
Other 3D printed fountain pens
My pens are by no means the first to be 3D printed. The pen company Additive specialises in 3D printed fountain pens that are very different from mine in looks and in the construction methods used. Perhaps I shouldn’t, but I will suggest that the Additive pens achieve only two of the three virtues mentioned above. Check them out here.
I have seen a few high-end ornate metal 3D printed fountain pens that achieve amazing levels of intricacy… at amazing prices. For example, see the pen reviewed here.
Finally, if you have a 3D printer and you would like to print your own pens then look at this project on Thingiverse for an open-source fountain pen.