A rotating tool system attachment on the spindle of a computer numerical control (“CNC”) machine includes a rotating assembly mounted on a static assembly. The rotating assembly provides a continuous supply of a wire material for deposition on a substrate during an additive manufacturing process. The rotating assembly includes a material supply housing a feedstock of wire mounted on a rotating spindle and a wire feeder configured to draw the wire from the wire supply and provide the wire for application during the additive manufacturing process. The tool system can be attached to the spindle of CNC machine to provide additive manufacturing capabilities to the CNC machine.