To extrude planar objects into 3D objects, in the Geometry toolbar, click 
Extrude (

). You can also right-click the 
Geometry or a 
Work Plane feature to add this from the context menu. Then enter the properties of the extrude operation.
 
    From the Extrude from list, select 
Faces to extrude planar faces from the 3D geometry. Select the faces that you want to extrude in the Graphics window. They appear in the 
Input faces list. All selected faces must lie in the same plane. Alternatively, from the 
Extrude from list, select 
Work plane to extrude objects from a work plane. In the 
Work plane list, select the work plane to extrude from. Select the objects that you want to extrude in the Graphics window. They appear in the 
Input objects list.
 
    From the Input object handling list, select one of the following options:
 
    Click the Active button to toggle between turning ON and OFF the 
Input objects selections.
 
    For Distances from plane, specify one or several distances (positive or negative) in the table. These determine the height above or below the work plane or planar faces for the top of each layer. The 
Reverse direction check box reverses the direction of the extrusion. To achieve a symmetric extrusion for a total thickness 
th, enter two distances: 
th/2 and 
−th/2.
 
    For Vertices to extrude to, select vertices to extrude the planar objects to from the list or by selecting them in the Graphics window.
 
    Select the Include input faces check box (selected by default) to also include a face of the extruded objects at their input location (the work plane). If you clear this check box, you do not get a face at the work plane, so the number of distances from the plane must be at least 2. Likewise, if you extrude to a single vertex, you need to include the input faces as a second end face for the extruded objects.
 
    Select the Resulting objects selection check box to create predefined selections (for all levels — objects, domains, boundaries, edges, and points — that are applicable) in subsequent nodes in the geometry sequence. To also make all or one of the types of resulting entities (domains, boundaries, edges, and points) that the resulting objects consist of available as selections in all applicable selection lists (in physics and materials settings, for example), choose an option from the 
Show in physics (
Show in instances if in a geometry part) list: 
All levels, 
Domain selection, 
Boundary selection, 
Edge selection, or 
Point selection. The default is 
Domain selection, which is suitable for use with materials and physics defined in domains. For use with a boundary condition, for example, choose 
Boundary selection. These selections do not appear as separate selection nodes in the model tree. Select 
Off to not make any selection available outside of the geometry sequence. From the 
Color list, choose a color for highlighting the resulting objects selection. See 
Selection Colors.
 
    
    From the Construction geometry list choose 
On to make the resulting objects available only in the feature’s geometry sequence. The default option 
Inherit means that the resulting objects become construction geometry if all input objects are construction geometry. Choose 
Off to never output construction geometry objects. For more information see 
Construction Geometry.