Abstract 3D Sand-Printing (3DSP) is a relatively new Additive Manufacturing (AM) technology that enables direct digital manufacturing (DDM) of complex sand molds and cores for sand casting applications. Ever-growing interest in this indirect hybrid metal AM process is attributed to its ability to rapidly produce tooling (i.e., cores and molds) for complex metal castings that are otherwise impossible to manufacture using conventional techniques. Knowledge-based design rules for this process is currently very limited and is being progressively realized on an ad-hoc basis to produce economicaly viable low-batch castings. In this research, non-conventional design rules for gating and feeding (also known as rigging) is developed to improve casting performance (i.e., filling, feeding and solidification). Several case studies are presented to illustrate the improved casting performance by systematically redesigning each element of the rigging system. Computational simulations of the melt flow are developed to evaluate the effectiveness of redesigned rigging system. This research further illustrates the ability of 3DSP to not only impact part performance, i.e., optimized metal casting designs via 3DSP but also drastically improves the casting performance which could potentially transform the industry of sand casting to produce high quality castings.