The Selective Laser Sintering (SLS) of pre-coated sands is a promising Rapid Prototyping technique for the construction of sand shells for foundry. In SLS, parts are made layer by layer, from plastic, metal, ceramic powders or pre-coated sands that are «sintered» using laser energy. The basic concept, common to all rapid-prototyping techniques, is that any complex shape can be obtained with the superposition of small thickness layers. The inherent material versatility of SLS technology allows a broad range of advanced rapid prototyping and manufacturing applications to be addressed. In this article, the definition of mathematical simulation concepts to predict the temperature distribution within the sand bed and the depth of the heat-affected zone (HAZ) is studied. The results obtained with the experimental methodology and those coming from previous experimental analyses have been used to validate the described mathematical model, which can be used for the process comprehension, control and optimization. The guidelines for future simulation refinements are also given.