A process for fabricating a unitized structure comprises creating a multilayer structure by applying a flame-retardant resin to a first layer and stacking, on the first layer, an intermediate layer comprising a honeycomb structure. Further, a second layer is stacked on the intermediate layer and the flame-retardant resin is applied to the second layer. The multilayer structure is then heated to a desired temperature and a pressure is applied about the multilayer structure for a predetermined process time. Moreover, the flame-retardant resin is prevented from entering spaces of the honeycomb structure. After elapse of the predetermined process time, the pressure is released, creating the unitized structure.