Editing Faces of a Solid by Extruding Faces
You can modify a 3D solid by extruding one or more faces of the solid. This can be a very powerful way to modify solids.
To extrude faces of a solid, on the Home ribbon, in the Solid Editing panel, click the Extrude Faces tool. The program prompts you to select faces. Click to select the faces that you want to extrude. When you select a face, it highlights. If you select a face that you do not want to extrude, right-click and choose the Remove option. The program then prompts you to remove faces. Click to select the faces you want to remove from the selection set. Once you have selected only the faces you want to extrude, press ENTER.
Next, the program prompts you to specify the height of the extrusion. You can enter a value or pick two points. If you pick points, the program uses the distance between the two points as the extrusion height. Type “10” and press ENTER.
Once you have specified the height of the extrusion, the program prompts you to specify the taper angle. A positive taper angle tapers the face inward as you move in the extrusion direction, whereas a negative angle tapers the face outward. Press ENTER to accept the current default taper angle of 0. As soon as you specify the taper angle, the faces are extruded perpendicular to the original face.
The command is still active and the program is prompting you to enter a face editing option. To extrude some additional faces, choose the Extrude option. The program prompts you to select faces. Click to select the faces on the inside of the portion of the solid you just extruded. Again, if you select a face by mistake, you can use the Remove option to remove that face and then use the Add option to select additional faces. Once you have selected the two faces, press ENTER. When the program prompts you to specify the height of extrusion, pick two points to specify an extrusion height of approximately 8 units. Then, specify an angle of taper extrusion of 15 degrees, and press ENTER. When you are finished extruding faces, you can use the eXit option to end the command, or simply press the ESC key.
The object would have been very difficult to modify in this way if you did not have the ability to extrude the individual faces.
When you extrude faces, instead of specifying the extrusion height, you can extrude the face along a path. Click the Extrude Face tool, click to select the top face of the cylinder, and then press ENTER. When the program prompts you to specify the height of extrusion, right-click and choose the Path option. The program prompts you to select the extrusion path. Click to select the blue polyline. The face is immediately extruded along that path.
Again, the command stays active so that you can use other face editing tools. You can use the eXit option to end the command, or simply press the ESC key.
Source: Autodesk
