260 AutoCAD and Its Applications—Advanced 260 AutoCAD and Its Applications—Advanced Converting Objects to Surfaces AutoCAD provides a great deal of fl exibility in converting and transforming objects. For example, a simple line can be quickly turned into a surface. Refer to Figure 10-26. 1. Use the Thickness property in the Properties palette to give the line a thickness. Notice that the object is still a line object, as indicated in the drop-down list at the top of the Properties palette. 2. Select the CONVTOSURFACE command. 3. Pick the line. Its property type is now listed in the Properties palette as a surface extrusion. Other objects that can be converted to surfaces using the CONVTOSURFACE command are 2D solids, 3D solids, arcs with thickness, open polylines with a thick- ness, regions, and planar 3D faces. NOTE NOTE The THICKNESS system variable can be used to assign a default Thickness property to new 2D objects that you create, such as lines, polylines, polygons, and circles. The value of the THICKNESS system variable does not affect the thickness of a planar surface or 3D surfaces. Thickening a Surface into a Solid A surface has no thickness. But, a surface can be quickly converted to a 3D solid using the THICKEN command. To add thickness to a surface, enter the THICKEN command. Then, pick the surface(s) to thicken and press [Enter]. Next, you are prompted for the thickness. Enter a thickness value or pick two points on screen to specify the thickness. See Figure 10-27. The THICKEN command can be used in conjunction with the CONVTOSURFACE command to quickly convert a 2D line into a solid. For example, create the line and then use the Properties palette to give the line a thickness. Convert the line into a surface using the CONVTOSURFACE command, and then use the THICKEN command to create a solid from the surface. CONVTOSURFACE Ribbon Home Solid Editing Convert to Surface Type CONVTOSURFACE THICKEN Ribbon Solid Solid Editing Thicken Type THICKEN Figure 10-26. Converting a line into a surface. First, draw the line. Next, give the line a thickness using the Properties palette. Then, convert the line to a surface using the CONVTOSURFACE command.