The process of rehydration of calcium sulphate hemihydrate (CaSO4.0.5H2O) to the crystallization of gypsum which is chemically known as calcium sulphate dihydrate (CaSO4.2H2O) is based on the amount of water added back. Plaster moulds are used to produce both ferrous and non-ferrous castings through investment casting process using slip casting techniques conventionally. The percentage water influences the properties of moulds and castings. Taking advantage of the rapid casting process a study was conducted to measure the effect of moisture in the moulds produced by three dimensional printing and it was found that the percentage moisture is directly proportional to the green compressive strength. L9 orthogonal array and the Box-Behnken design of experiments were used to study the effect of the percentage moisture in the mould.