A sintering system for manufacturing a three-dimensional object from sinterable powder, the system comprising: a build chamber comprising a movable floor and four side walls; an energy assembly (10, 12) disposed above the build chamber, comprising at least one energy source adapted to emit an energy beam; a feeding assembly connected to the build chamber for providing sinterable powder to the build chamber; a powder distribution device connected to the feeding assembly for distributing sinterable powder in the build chamber; characterized in that the build chamber further comprises: opposite openings in two side walls, below which the movable floor can be lowered; and a cover arranged at a predetermined level above the opposite openings, closeable after the moveable floor has been lowered below the predetermined level, which cover, when closed, is configured to seal a build chamber portion between the closed cover and the moveable floor when the moveable floor is lowered below the openings; and a pneumatic assembly (24, 26) connected to the sealed build chamber portion for transporting powder away from the sealed build chamber portion through at least one of the openings, wherein the pneumatic assembly (24, 26) comprises a first combined suction/fan unit at one side opening, and a second combined suction/fan unit at the opposite side opening, the combined suction/fan units adapted to alternately provide suction and blowing to the sealed build chamber portion via their respective side openings. a build chamber comprising a movable floor and four side walls; an energy assembly (10, 12) disposed above the build chamber, comprising at least one energy source adapted to emit an energy beam; a feeding assembly connected to the build chamber for providing sinterable powder to the build chamber; a powder distribution device connected to the feeding assembly for distributing sinterable powder in the build chamber; characterized in that the build chamber further comprises: opposite openings in two side walls, below which the movable floor can be lowered; and a cover arranged at a predetermined level above the opposite openings, closeable after the moveable floor has been lowered below the predetermined level, which cover, when closed, is configured to seal a build chamber portion between the closed cover and the moveable floor when the moveable floor is lowered below the openings; and a pneumatic assembly (24, 26) connected to the sealed build chamber portion for transporting powder away from the sealed build chamber portion through at least one of the openings, wherein the pneumatic assembly (24, 26) comprises a first combined suction/fan unit at one side opening, and a second combined suction/fan unit at the opposite side opening, the combined suction/fan units adapted to alternately provide suction and blowing to the sealed build chamber portion via their respective side openings. opposite openings in two side walls, below which the movable floor can be lowered; and a cover arranged at a predetermined level above the opposite openings, closeable after the moveable floor has been lowered below the predetermined level, which cover, when closed, is configured to seal a build chamber portion between the closed cover and the moveable floor when the moveable floor is lowered below the openings; and a pneumatic assembly (24, 26) connected to the sealed build chamber portion for transporting powder away from the sealed build chamber portion through at least one of the openings, wherein the pneumatic assembly (24, 26) comprises a first combined suction/fan unit at one side opening, and a second combined suction/fan unit at the opposite side opening, the combined suction/fan units adapted to alternately provide suction and blowing to the sealed build chamber portion via their respective side openings.