I needed to make the fitting of the clevis a bit tighter so the elbows would not be so wobbly.

This thing is a little bit more precise, when mated with the current female version: http://www.thingiverse.com/thing:8129

By default, the diameter of the opening is 1/4", which is perfect to fit a steel dowel pin as an axle.

The depth is 3/8" by default, which is perfect to fit two of these on the ends of a steel dowel pin that is 1 1/4", leaving 1/2" gap between them.

So, these two things combined form a nice elbow joint where one end is 1/4" and the other is 5/16", or whatever sizes you need.

1) Print a few of these
2) Slip onto the end of a 1/4" rod of some sort
3) Rejoice!

It is a tight friction fit. You might want to add a bit of epoxy depending on your usage.

You can also print it a fraction of a millimeter smaller, and use a heat gun to relax it while doing an even tigher friction fit. I find the fit to be just fine for my 1/4" steel dowel pins.