Molded electronics package cavities are formed by placing a sacrificial material in the mold and then decomposing, washing, or etching away this sacrificial material. The electronics package that includes this sacrificial material is then overmolded, with little or no change needed in the overmolding process. Following overmolding, the sacrificial material is removed such as using a thermal, chemical, optical, or other decomposing process. This proposed use of sacrificial material allows for formation of complex 3-D cavities, and reduces or eliminates the need for precise material removal tolerances. Multiple instances of the sacrificial material may be removed simultaneously, replacing a serial drilling process with a parallel material removal manufacturing process.