An ink-jet printing mechanism has been designed to fit inside the Sinterstation 2000 machine for making color selective laser sintering (SLS) prototypes. A number of experiments were carried out that include a decision on printing before sintering or after sintering. There is also a decision on the ink to ethanol ratio that is suitable for color SLS printing. This depends on the ink penetration rate, the effect of ethanol, the color of ink and structure of SLS materials, and the stability of ink inside the SLS build-chamber. The thermal properties of the powder will be changed by the addition of the ink. This will affect the prototype's physical properties like curling effect or mechanical properties like tensile strength. These effects are discussed in this paper.