Abstract:
The invention provides an apparatus for building a three-dimensional article in sequential cross-sectional layers, which apparatus comprises: a powder delivery system comprising one or more reservoirs for delivering a powder and a powder spreading system; a printing system for delivering a liquid; a build chamber comprising a outer wall, an inner wall and a build platform which is movable along the inner wall of the build chamber; and a powder recovery system; wherein the building chamber comprises a space defined by the upper portion between the inner wall and the outer wall of the building chamber and this space is in communication with the powder recovery system and/or the build platform is capable of releasing unused powder (directly) from the build chamber in a downward direction into the powder recovery system. The invention further provides a method building a three-dimensional article wherein use is made of said apparatus.