3 axis CNC control....Hmmmmm.....the EDm produces the cavity etc by using a formed copper/graphite etc electrode, during which the end is gradually eroded away also, but the cavity formed is the shape of the electrode, unless you mean that the electrode is a square or round section and the form is produced by weaving around a shape under CNC control, which means then that all you need is the EDM circuits and the rest is normal CNC layout?
There are real plans to produce the sparking process, but they are pretty standard anyway.
Ian.