The invention describes an ink formulation and method of making a 3D printed RF device. The ink consists of a triblock copolymer in a solvent, and one or more additives that can enhance the flow of the ink and improve properties of the end structure, including dielectric properties. The ink is viscoelastic, allowing for greater control over the rate and method of flow. The ink can include dielectric filler particles that alter the RF properties in a predictable fashion while maintaining micron scale resolution. The method describes extruding an ink formulation from a deposition nozzle moving relative to a substrate, which can increase the range of geometries of 3D structures to be built layer by layer. One or more continuous filaments comprising the ink formulation can be deposited in a predetermined pattern on the substrate. Once printed, the ink formulation is treated to remove or cure the solvent, thereby forming a printed RF device. Notably, this materials system and printing process allows for the fabrication of devices whose properties can be tailored in a graded pattern avoiding abrupt interfaces within the part.