After selecting the body of interest: Select Color in the Display ribbon under the Style section, and then click the Opacity bar to change the opacity of the model. or Use the Color or Style Override tools, located in the Display ribbon under the Style section to set opacity for selected objects. Style Override makes the object opaque or transparent, regardless of face or layer settings. These overrides are automatically deselected when you change the transparency of an object using the Color tool or Style Painter.