Which tool can be used to create custom meshes in Unity?

The Poly Shape tool is specifically designed to facilitate the creation of custom meshes within Unity. Unlike other tools that play different roles, the Poly Shape tool provides an intuitive interface that allows artists to define the shape of a mesh by manipulating vertices, edges, and polygons directly in the Unity Editor. This is particularly useful for creating unique game assets or environments that do not fit standard shapes.

While the Mesh Renderer is crucial for displaying meshes by handling how they are rendered in the scene, it does not actually create the meshes themselves. The Terrain Tool is oriented towards designing landscapes and terrains, using pre-defined features and textures, which limits its use for custom mesh creation. The Lighting panel deals with how light sources affect objects in the game environment and is not related to mesh creation.

In essence, the Poly Shape tool stands out as the primary tool for artists looking to design and construct unique geometric forms directly within Unity's development environment.