To add a model view, right-click the 'Model View' node in the Project Explorer and choose 'New Model View' from the context menu. Alternatively you can select Project -> New -> Model View... from the main menu or click the button in the toolbar to create a new model view. Using these options will result in a new, empty model view.
You can also create a new model view and directly add entities to it. To do so, select one or more entities in the Project Explorer and select Add Selected Entities to Model View... By specifying a new model view name, a new model view will be created.
You can also create a new model view based on search results (if the search result is a set of entity definitions) in Element Search result tab. Specify a new model view name in the dialog presented.
From an existing model view, or inheritance hierarchy tab you can also create a new model view based on the entity definition selected: select one or more entity definitions and right-click the selection and select Add Selected Entities to New or Existing Model View from the context menu.