A grid of 18 smiley faces, each randomly varied in eye size, mouth width, and stroke thickness, demonstrates how React components can render SVG primitives while leveraging D3 for geometry. The example uses React to compose reusable `Face`, `BackgroundCircle`, `Eyes`, and `Mouth` components, with D3's `arc` generator defining the mouth path and `range` creating the grid array. Each face is drawn with randomized parameters, showing how declarative UI structure and imperative D3 math can coexist within a single visualization.