Methods and rail supports for additive manufacturing

A method for fabricating an object, comprising:

• (a) irradiating a layer of powder in a powder bed with an energy beam in a series of scan lines to form a fused region;
• (b) providing a subsequent layer of powder over the powder bed by passing a recoater arm over the powder bed from a first side of the powder bed to a second side of the powder bed;
• and
• (c) repeating steps (a) and (b) until the object and at least one support structure is formed in the powder bed,
• wherein the at least one support structure includes a plurality of substantially parallel vertical walls, each wall extending substantially parallel to a direction from the first side to the second side;
• wherein adjacent walls of the plurality of substantially parallel vertical walls are separated by a continuous portion of unfused powder;
• and
• wherein the object is formed above the plurality of parallel vertical walls.