An additive-manufacturing apparatus, comprising: a support; a powder-material source; a powder-supply arm, having a powder-supply-arm central axis and comprising: a hollow body, having an interior volume that is in communication with the powder-material source such that a powder material can be transferred from the powder-material source to the interior volume; a powder-deposition opening in the hollow body, and wherein the powder-deposition opening has a width and is in communication with the interior volume of the hollow body such that the powder material can be transferred out of the interior volume through the powder-deposition opening; and a powder-distribution blade, coupled to the hollow body and extending along the powder-deposition opening; an energy source; an energy-supply arm, having an energy-supply-arm central axis; energy emitters, coupled to the energy-supply arm, and wherein the energy emitters are configured to be in one of electrical or optical communication with the energy source; and a rotary drive, configured to rotate the powder-supply arm and the energy-supply arm about a vertical axis, passing through the support, and intersecting the powder-supply-arm central axis and the energy-supply-arm central axis, wherein: the powder-supply arm further comprises a door, coupled to the hollow body; the door is movable relative to the hollow body to at least partially open or to close the powder-deposition opening; and when the door is positioned relative to the hollow body of the powder-supply arm so that the powder-deposition opening is partially open, the width of at least a portion of the powder-deposition opening increases along the powder-supply-arm central axis of powder-supply arm 108 in a direction away from the vertical axis. a support; a powder-material source; a powder-supply arm, having a powder-supply-arm central axis and comprising: a hollow body, having an interior volume that is in communication with the powder-material source such that a powder material can be transferred from the powder-material source to the interior volume; a powder-deposition opening in the hollow body, and wherein the powder-deposition opening has a width and is in communication with the interior volume of the hollow body such that the powder material can be transferred out of the interior volume through the powder-deposition opening; and a powder-distribution blade, coupled to the hollow body and extending along the powder-deposition opening; a hollow body, having an interior volume that is in communication with the powder-material source such that a powder material can be transferred from the powder-material source to the interior volume; a powder-deposition opening in the hollow body, and wherein the powder-deposition opening has a width and is in communication with the interior volume of the hollow body such that the powder material can be transferred out of the interior volume through the powder-deposition opening; and a powder-distribution blade, coupled to the hollow body and extending along the powder-deposition opening; an energy source; an energy-supply arm, having an energy-supply-arm central axis; energy emitters, coupled to the energy-supply arm, and wherein the energy emitters are configured to be in one of electrical or optical communication with the energy source; and a rotary drive, configured to rotate the powder-supply arm and the energy-supply arm about a vertical axis, passing through the support, and intersecting the powder-supply-arm central axis and the energy-supply-arm central axis, wherein: the powder-supply arm further comprises a door, coupled to the hollow body; the door is movable relative to the hollow body to at least partially open or to close the powder-deposition opening; and when the door is positioned relative to the hollow body of the powder-supply arm so that the powder-deposition opening is partially open, the width of at least a portion of the powder-deposition opening increases along the powder-supply-arm central axis of powder-supply arm 108 in a direction away from the vertical axis. the powder-supply arm further comprises a door, coupled to the hollow body; the door is movable relative to the hollow body to at least partially open or to close the powder-deposition opening; and when the door is positioned relative to the hollow body of the powder-supply arm so that the powder-deposition opening is partially open, the width of at least a portion of the powder-deposition opening increases along the powder-supply-arm central axis of powder-supply arm 108 in a direction away from the vertical axis.