Four types of high-permittivity and low-loss electromagnetic composites for Fused Deposition Modeling (FDM) based on Cyclo-Olefin Polymer (COP) and Acrylonitrile Butadiene Styrene (ABS), reinforced by Ba0.55Sr0.45TiO3, MgCaTiO2, or TiO2 co-fired micro-fillers, have been prepared and characterized up to 17 GHz using cavity resonators. Thin-sheet specimens made of 25% v/v COP-MgCaTiO2, prepared by FDM, exhibit a relative permittivity εr of ∼ 4.74 and loss tangent tanδd lower than 0.0018, while 25% v/v COP-Ba0.55Sr0.45TiO3 specimens exhibit relative permittivity εr of ∼ 4.92 and loss tangent tanδd lower than 0.0115. Meanwhile, 30% v/v COP-TiO2 specimens exhibit a relative permittivity εr of ∼ 4.56 and a record low loss tangent tanδd lower than 0.0014, while the 6% v/v ABS-Ba0.55Sr0.45TiO3 specimens demonstrate relative permittivity εr of ∼ 3.98 and loss tangent tanδd below 0.0088. Rectangular edge-fed patch antennas operating at ∼ 17 GHz are fabricated using 3D printing to compare the size and performance against designs that used commercial microwave laminates.