I gottcha ,Graham.I like this way and since what I want is high contrast ,any discontinuity will just be part of the randomness.What I think I would do is outline the high contrasted image in Rhino.Draw the circles and then 'trim' the first area of interest and save it as a layer and then continue to isolate each circle and save as another layer this way,generate the gcode from importing it as a DXF and then do the trig to insert into each layer's z-cut.Thanks a million.-Keith