ZrC/W-based composites with complex shapes have been fabricated by combining rapid prototyping methods for synthesizing porous WC preforms with the shape/dimension-preserving, reactive infiltration-based Displacive Compensation of Porosity (DCP) process. Two automated rapid prototyping methods were examined: (i) computer-numerical-controlled machining of porous WC powder compacts, and (ii) 3D printing of WC powder. After binder removal and partial sintering (to neck the WC particles), the shaped, porous, and rigid preforms were exposed to molten Zr2Cu at 1150-1300°C and ambient pressure. Upon infiltration, the Zr in the melt underwent a displacement reaction with WC to yield more voluminous ZrC and W products that filled prior pores (reaction-induced densification). The resulting ZrC/W-based composites retained the shapes and dimensions (to within 1%) of the WC preforms. This work demonstrates, for the first time, that rapid preform prototyping can be integrated with the DCP process to generate dense, ultrahigh-melting carbide/refractory metal composites with tailorable near net-shapes and -dimensions.