You can work with two types of 3D objects in AutoCAD: solids and surfaces. You can treat both solid and surface objects as if they were solid material. For example, you can create a box and then remove shapes from the box as if you were carving it, as shown in Figure 6.6.

Figure 6.6: Solid modeling lets you remove or add shapes.

With surfaces, you create complex surfaces shapes by building upon lines, arcs, or polylines. For example, you can quickly turn a series of curved polylines, arcs, and lines into a warped surface, as shown in Figure 6.7.

Figure 6.7: Using the Loft tool, you can use 2D objects to define a complex surface.

In the first part of this section, you ll learn how to create a solid box, and at the same time, you ll be introduced to some of the more common modeling features. The next part shows you how to create a surface model. You ll get a chance to see how surface modeling differs from solid modeling, and you ll learn how each modeling method is best used.