A gas supply system for the a protective atmosphere in apparatus for the production of metallic components by additive manufacturing includes a gas induction housing mountable at a first location of a housing processing chamber housing, having an inlet port and an outlet opening with the inlet port connectable to a source of protective gas for the processing chamber to enable a flow of the gas to the processing chamber. The system further includes an eduction housing mountable at a second location of the processing chamber, having an inlet opening and an outlet port to enable gas to be drawn from the processing chamber, into the eduction housing, for discharge from the outlet port.