Which of these cannot be defined as reusable objects in the Reuse Library?

In the context of the Reuse Library in Siemens NX, reusable objects are components or entities that can be stored and utilized in multiple designs to enhance efficiency and consistency. The correct choice, which is visualization material, cannot be defined as a reusable object in the same sense as the other options.

Visualization materials are primarily used for rendering and visual representation purposes within the software. They focus on the appearance of objects rather than their structural or functional properties. While you can apply visualization materials to parts or assemblies, they do not have a functional role in the design process like 2D section sketches, features, and assemblies do.

2D section sketches are essential for creating profiles and contours in designs, features encapsulate specific design tasks or operations (such as extrusions or fillets), and assemblies allow for the grouping of multiple parts to form a complete system or product. Each of these can be saved and reused across different projects to streamline workflows and maintain design integrity. In contrast, visualization materials can vary based on individual preferences and project requirements, thus making them unsuitable as reusable objects in the context of functional design elements.