A prototyping process based on the technique of selective ${CO_2}$ laser sintering has been carried out using bronze powder. The integration of a ${CO_2}$ laser and a working table to create the opto-mechanical system has been constructed for making the multi-layer sintering. Three dimensional rapid prototyping process which has used the 40W ${CO_2}$ laser and bronze powder has been investigated experimentally The optimal scanning method has been found to minimize the deflection and distortion by using the thermal strain method which the laser scans in the x and v directions repeatedly. The method of spreading powder has been improved by using the rubber knife of which the flexibility causes less wave of spreading powder.