Abstract: An apparatus for forming 3D objects from metallic powder, includes a delivery mechanism adapted to emit a flow of metallic powder at sufficiently high velocity to enable it to form a solid mass on a substrate; and a positioning mechanism adapted to set or adjust the distance and/or angle between the delivery mechanism and the substrate as powder builds up on the substrate. A control system is adapted to receive measured geometry data representing the state of the object as it builds and to control adjustment of the positioning means in response to that data for accurate formation of the object.