Abstract: A method for forming at least one three-dimensional article through successive fusion of parts of a powder bed, which parts correspond to successive portions of the three-dimensional article, said method comprising the steps of: providing at least one model of said three-dimensional article, wherein said model of said three-dimensional article is described in a 2-dimensional angular coordinate system; applying a powder layer on a support structure; directing at least one energy beam from at least one energy beam source over said powder layer causing said powder layer to fuse in first selected locations according to said model to form a first portion of said three-dimensional article, providing a first portion of said powder layer simultaneous as fusing a second portion of said powder layer, wherein said second portion of the powder layer is fused along a line perpendicular to a rotational axis of said support structure.