This is an oblique nib holder I designed for trying Copperplate or other styles which are slanted, making it easier to write with an oblique-style holder. The example is printed in PLA, with a fairly low infill, and .4mm layer height, but as long as the nib-holding geometry comes out well, it shouldn't matter. The nib face is flat and the pen should be printed upright with no supports.

Fitted for a standard G nib (I use Zebra G nibs, which are inexpensive and flex well). The nib should be lightly scrubbed with a paper towel and toothpaste before use to remove the protective oil and help with ink adhesion. I have found these to work well with a variety of standard fountain pen inks.

If needed, an exacto can be used to clean out the nib-holding slot. Over time if a nib is left in, the material will flex and lose tension, resulting in a loose nib. I use a small dab of superglue for security.