This paper presents an investigation on thermal and mechanical properties of new metal-particle filled Acrylonitrile Butadiene Styrene (ABS) composites for applications in Fused Deposition Modeling rapid prototyping process. Test samples of Iron/ABS and Copper/ABS composites involving metal content up to 40% by volume have been made by controlled centrifugal mixing, thermally compounded through a single-screw extruder and compression moulding. Dynamic Mechanical Analysis (DMA) techniques were used in order to characterize viscoelastic properties of these newly developed composites materials for use in Fused Deposition Modeling process. It has been shown that significant improvements of ABS thermal and mechanical properties due to incorporation of metallic fillers can potentially promote processing of high performance and functional prototypes on the existing FDM platform for a wide range of applications. Sample prototypes from the new composite materials have been successfully made and tested.