Copyright Goodheart-Willcox Co., Inc. 284 AutoCAD and Its Applications—Advanced Extruding a Solid Face Planar faces on 3D solids can be extruded into new solids. Refer to the HVAC duct assembly shown in Figure 11-19A. A new, reduced trunk needs to be created on the left end of the assembly. This requires two pieces: a reducer and the trunk. Base point C A B Base point A B Face being rotated Figure 11-16. A—Rotating a face without pressing the [Ctrl] key. The large, top face on the object has been selected for rotation. B—Pressing the [Ctrl] key once keeps the adjacent faces in their original planes. The shape and size of the face being rotated changes. Figure 11-17. Scaling a face. A—The original solid. B—The dark face is scaled down. C—The dark face is scaled up.