Finished machining these today, adding the pocket to fit the carbon fiber arm tube.  Drilled the corners first so that I could machine the rest of the pocket square with a .0625 end mill.  Everything fits pretty well, which can be challenging at this scale.
This weekend I hope to draw up the center portion of the quad, basically an "X" shape that will hold the arms, control board, and underneath it, the flight battery.
I still have to modify the brushless speed controllers as well.  More on that when I get to that stage.