There are numerous benefits for creating your part design as a multibody part ranging from performance to file management in SOLIDWORKS. However if you have tried to apply a material to a multibody part you will notice that the materials folder of the feature manger will apply the same material to every single body in your design. This works fine if you have a weldment structure which is all made out of steel, but most designs use a combination of materials to accomplish their design goals. In this example for a conveyor belt, there could be aluminum, steel and even rubber. One material could be applied to the entire design, however our mass property and simulation results would be inaccurate.
Instead of saving the bodies individually and importing them into an assembly in order to accurately apply the material to each body. One can expand the cultist folder and search for the body that they would like to apply a material to. Once found, simply right click on that body and choose the material tab. This will reveal the exact same material options that are normally found in the material folder of the feature manager, however this will only change the material properties of this one individual body.
If you have a larger design like this conveyor, than manually apply a material to each body can be time consuming and cumbersome. Instead the same functionality is available by Ctrl or Shift selecting multiple bodies and apply a material to those bodies as a group. All of the same benefits of creating multibody parts are achieved without losing the ability to apply different materials to multiple bodies.