User Guide > Rendering and Render Setup > Shading > Shading menus > Rendering menu set > Lighting/shading >

Lighting/shading > Assign Existing Material

Assigns one of the shading groups in the Assign Existing Material sub-menu to all selected surfaces. This menu updates depending on the materials you create.

For more information on the shading group, see Shading group node.
For more information on materials, see Surface, displacement, volumetric materials.