Homebrew PCBs

I know, someone else has already thought of this but if not, here is 
an idea.

A while back I suggested the possibility of an altered ink jet 
printer that could be used to print resist onto a circuit board.

Another idea I had was to use a plotter (or even a CNC machine) and 
a resist pen to draw out the resist areas.  I have not used a resist 
pen yet, so I don't even know how fine of a line you can draw with 
them but I think you get the idea.

I know, you are thinking "If I have a CNC router, why not just mill 
the trace outlines". I agree, but I am just wondering which would be 
more efficient with regard to time and tooling.  Those little mills 
are pretty pricy and I would guess they don't last very long.  But, 
at the same time, I am not sure of the cost of etchants and resist 
pens.

Just some thoughts I need to share and ponder.