Apparatuses, systems and methods for three-dimensional printing

A method for generating a three-dimensional object, comprising:

• (a) providing a powder layer in an enclosure to form a powder bed, wherein the powder layer comprises individual particles formed of at least one member selected from the group consisting of an elemental metal, metal alloy, ceramic, and an allotrope of elemental carbon, wherein upon providing the powder layer in the enclosure, the individual particles of the powder bed are flowable;
• (b) transforming a portion of the powder bed into a transformed material;
• and
• (c) hardening the transformed material to form at least one layer of hardened material as part of the three-dimensional object,
• wherein each of the at least one layer of hardened material has a radius of curvature of at least about 5 centimeters as measured by optical microscopy, and wherein, with X and Y being points on a surface of the three-dimensional object, (i) the surface of the three-dimensional object that intersects a sphere of radius XY at positions X and Y is devoid of an auxiliary support feature, and (ii) an acute angle between a straight line XY and a direction normal to an average layering plane (N) of the at least one layer of hardened material is from about 45 degrees to 90 degrees when X and Y are spaced apart by at least about 2 millimeters.