My wife got me a dip pen as a gift, and I like it but I had a problem with the black ink paint bottle we have being too thin to dip the pen in, so I build a little ink cup that is just the size of the pen tip for convenience and less waste , and the format was chosen because its the most stable and hard to spill. I've printed it in ABS, but I guess any material should do, the important part is to make sure you print is airtight so the paint don't just pass through the material, I did it by making the 4 layers wall count. and it worked fine. you could also use the a Pyramid to hold the pen in vertical putting the pen ends on the Pyramid hole.

a small trivia is that i made the angle to be close to one of the Giza Pyramids