The possibility of using materials with better physical and mechanical properties together with the quickly improving capabilities of various processes increasingly make Rapid Prototyping (RP) as a new manufacturing technology for specialty components. In Fused Deposition Modeling (FDM), the build orientation and the toolpath used strongly affect the properties of the part. This study presents the results of experimental work based on mechanical characterization of parts fabricated with fused deposition to determine the stiffness matrix and the thermal expansion coefficients for an equivalent orthotropic material. The results can be directly adapted into computational analysis tools based on classical lamination theory, for part quality and performance prediction. Current investigation focuses on use ofABS material in Stratasys FDM 1650 rapid prototyping equipment.