The purpose of the present experimental investigations is to study the effect of work piece dimensions on reducing the shell wall thickness of mould cavity for cost effective, hybrid rapid casting solution of aluminum alloy. Starting from the identification of component/benchmark, technological prototypes with three different work piece dimensions (volume/ weight) were produced, at different shell wall thickness of mould cavity using hybrid rapid prototyping technique (combination of three dimensional printing and conventional sand casting). Measurements on the coordinate measuring machine helped in calculating the dimensional tolerances of the castings produced. Some important mechanical properties were also compared to verify the suitability of the castings. The study suggested that the shell wall thickness, having value less than the recommended one is more suitable from dimensional accuracy and economic point of view, for all three work piece dimensions (volume/ weight). Further best shell wall thickness of the mould cavity for different work piece dimensions of the selected benchmark has been highlighted for rapid casting solution of aluminum alloy.