to assemble, print two of these, and stick the pin through both of them.  it might take some force, or a round file to get it to fit, but you want it to be snug.

then just glue the two halves together with some superglue, make sure the end is well alligned so it forms a nice square shape as it dries.


I didn't have a full stem to copy one to one, as mine broke, so a few measurements i had to make up.
the images listed have the measurements i need, if you send them to me i will update the model.