Use the Solid Faces page of the New Feature wizard to select solid faces that represent a feature.
Add faces you want to machine to the list using the buttons:
Slicing heights — Select Manual and specify the top and bottom heights of the feature, or select Automatic to use the height of the surfaces as the height of the feature.
Hide surfaces when finish — Select this option to hide surfaces used to create the feature when you finish the wizard.
Preview — Display a preview of the feature in blue in the graphics window.