If Building, I am sure that a fixed gantry machine would be best for you, but I personally think that you would be better to go down the milling machine route, not a manual machine converted, but a purpose made CNC mill. Something like a Boxford or a Denford machine. There are quite a few that have already been changed to run with Mac3, but I understand that the later machines used a usb interface and had good CASD/CAM software. G.