Abstract: In this paper, we examine how the support structure in 3D-printing can be optimized, by changing a model׳s orientation. Specifically, we explore the effect that the orientation of a printed object has on the volume of the needed support structure, directly below the model. We show that the volume of the support is a continuous but non-smooth function, with respect to the orientation angles. We continue by presenting an efficient algorithm, capable of running on a GPU, that computes the model׳s support volume for a given orientation. Then, this algorithm is used to find an orientation with a minimal volume of support for constructing the model, that is not necessarily optimal. However, examples and experimental results are presented, showing that the minimum computed by our approach is for practical purposes, in many cases, optimal.