Homebrew PCBs

I was suggesting not to remove the copper, but to remove the paint.  After the paint is removed, place the board in etchant and etch.  The copper will remain where the paint was not removed leaving the traces.  Or is this what you meant when you said it would not work?

--- In Homebrew_PCBs@yahoogroups.com, "Jeff" <jeff.heiss@...> wrote:
>
> I have an idea for making boards using Electrical Discharge Machining (EDM) that I would like to bounce off you guys.
> 
> The idea is to use a needle on a CNC x-y table (picture pen plotter with the pen replaced with the needle).  The needle hovers just above the copper board a few thousandths, maybe .003" – .006".  Paint the copper with automotive spray paint.  Apply a high-voltage/high-current to the needle and ground the board.  The spark between the needle and copper will burn and evaporate away the paint.  The board could be submerged in oil or some dielectric to keep oxygen out.  The artwork drawn would be like that of a milled board where the copper around the traces is removed or all copper could be removed with multiple back and forth scans over the whole board.
> 
> What do you guys think?  Would acceptable trace spacing and widths be achievable?
>