An improved bubble wand assembly for a motor driven, bubble producing toy is provided. Lens frame hold portions, which restrict rotation of the first lens frame about an optical axis and movement of the first lens frame in a right-and-left direction, are formed on both sides of the fixing slit. The stability of the surface of the silicon wafer is assured by optimizing to minimize particle addition at each step. The device programs and reads data in a pair of memory cells using three bits of data corresponding to three threshold voltage distributions of the 3-level nonvolatile memory cells. In particular, methods for enhancing the cargo-carrying capacity of such a vehicle beyond a manufacturer’s specified cargo weight capacity are provided.