The current hydrogel self-inflating expander is limited by its volume and linear expansion rate, making it unsuitable for correcting patient-specific large mandibular bone defects in soft-tissue surgeries. This study devised a novel approach for crafting patient-specific gingival tissue expanders for large mandibular bone defects by employing silicone 3D-printing technology. The biocompatible and swellable polymer tablet was compressed and placed into a 3D-printed silicone membrane to evaluate its expansion capability. Two patient-specific large left and right mandibular bone defects with complex geometries were selected to generate defect expander models in a computer-aided design (CAD) software. The swellable tablets were enveloped in the 3D-printed silicone membranes to form soft-tissue expanders, which were then immersed in phosphate-buffered saline (PBS) for 6 weeks to observe their expansion. Results demonstrated that a slot-shaped silicone soft-tissue tablet attained an expansion volume of 1960 mm³. A fourth-degree polynomial fitting curve illustrated slower expansion rates in the initial 2 weeks and achieved complete expansion in about 6 weeks. Patient-specific silicone expander testing indicated less than 2% error in the average expanded volumes of compared to CAD models. The cross-sectional profile of the soft-tissue expanders closely resembled the CAD model. This study demonstrated that biocompatible polymer could be utilized as swellable tablet material and enveloped within a 3D-printed silicone membrane to generate a novel soft-tissue expander that adhered to clinical standards. Additionally, the study validated the feasibility of expanding patient-specific silicone expanders within 6 weeks for repairing large left and right mandibular bone defects.