A radiation curing composition suitable for building a three-dimensional object by a solid freeform method is disclosed. The composition includes one or more mono-functional monomers where a respective polymer has a Glass Transition Temperature higher than about 60° C., one or more di-functional oligomers where a respective polymer has a Glass Transition Temperature lower than about 40° C. and a phase separation inducing component. The phase separation may be induced during curing, resulting in a non-clear cured material having an improved impact strength and higher elongation, when compared to similar compositions without a phase separation including component.