Changes

First click either on the surface of "Box_1" or on its name in the navigation tree to select the object to subtract form. Then press the keyboard's {{key|Enter}} key to signal the completion of the object selection. Next select the names of "Hole_1" and "Hole_2" from the navigation tree. These are the objects to be subtracted. You can also click on the surface of these objects in the project workspace although it might be harder due to mouse-over conflicts. Since you can select multiple objects for subtraction, you have to press the keyboard's {{key|Enter}} key to signal the completion of the object selection.