This 3D-printed model draws its design inspiration from an “underwater torpedo,” ingeniously blending a streamlined, shark‑inspired silhouette with principles of buoyancy. The overall form exhibits exceptional hydrodynamic efficiency. To play, the model must be fully pressed beneath the water’s surface; as it displaces water, the resulting strong positive buoyancy imparts an upward initial velocity upon release, enabling a dramatic splash‑and‑leap effect that combines underwater exploration with dynamic surface action. In terms of printing requirements, since this toy is intended for repeated submersion and demands precise weight control and a smooth surface finish, it must be printed using **highly waterproof PETG material that resists water absorption and softening**, rather than standard PLA. During slicing, enable “spiral vase mode” or employ extremely thin layer heights to minimize interlayer friction, yielding an exceptionally smooth exterior that greatly reduces water resistance and ensures a swift, fluid launch with every press.