A rapid prototyping process for manufacturing complex three-dimensional RF structures in ceramic systems was developed. The process combines fundamentals from lost wax investment casting and ceramic gelcasting. The first step is to directly deposit a mold made of a low melting point wax using a high precision inkjet rapid prototyper. Then, a gelcasting slurry containing polymeric precursors, a high solids loading of ceramic powders and a free radical initiator is cast into the mold and polymerized to lock in the structure. Finally, the mold is melted and the remaining green part is sintered. Aqueous gelcasting slurries were developed for MgCO3, (Ba,Sr)TiO3, and a composite of (Ba,Sr)TiO3 and MgO. The maximum solids loading attained for each of the powders was 22 V%, 50 V%, and 25 V% respectively. The 50V% gelcast part had a more uniform microstructure, higher sintered density, less open porosity and smaller grain size than parts produced through dry pressing. The microstructural improvements resulted in a high dielectric permittivity.