Tailored magnetic nanocomposites have applications ranging from communications technologies to medical devices. Using a novel 3D fabrication technique that combines thermal inkjet and powder bed fusion print technologies, magnetic composites were fabricated by jetting magnetic nanoparticle containing ink into a polymer powder bed and then heat fusing the ink/polymer matrix. The goals were to demonstrate the feasibility of nanocomposite fabrication with controllable magnetic properties by varying the volume fraction of magnetic ink jetted into the polymer as well as to experimentally validate the effective medium theory based model developed to predict the permeability of the composites as a function of its magnetic particle concentration. As expected, magnetic susceptibility and saturation magnetization were seen to increase with the volume fraction of magnetic particles in the composites.