An apparatus for forming at least one three-dimensional article through successive fusion of parts of a powder bed. The apparatus comprises a powder distributor configured for evenly distributing a layer of powder on top of a build table; an energy beam configured for fusing the powder layer in selected locations corresponding to the cross section of the three-dimensional article, the powder distributor comprises an elongated rod provided movable at a predetermined distance above the powder table and with its central axis in parallel with a top surface of the powder table, and a flexible foil attached onto the elongated rod and protruding from the rod towards the powder table; and an elongated device parallel with the powder distributor and arranged onto or over the powder table outside the build table, where the elongated device is arranged for mechanically touching the flexible foil.