Abstract: The present disclosure provides three-dimensional (3D) printing methods, apparatuses, and systems using, inter alia, a controller that regulates formation of at least one 3D object (e.g., in real time during the 3D printing); and a non-transitory computer-readable medium facilitating the same. For example, a controller that regulates a deformation of at least a portion of the 3D object. The control may be in situ control. The control may be real-time control during the 3D printing process. For example, the control may be during a physical-attribute pulse. The present disclosure provides various methods, apparatuses, systems and software for estimating the fundamental length scale of a melt pool, and for various tools that increase the accuracy of the 3D printing.