94 Product Design, Computer Aided Design (CAD), and Solid Modeling Chap Ilemporaryoonstructionlines(ceanddf) Figure 3.9 Outline of the base exterior before the trimming process F1gure3.10 Outline of the base exterior after the trimming process A good place to start is the shallow rounded pocket in the bottom face, because many consumer electronics products, including telephones, have a cover plate on the bottom This is more like a shallow recess that the cover plate will eventually nestle into The cover plate will close over the larger internal cavity that houses the printed circuit boards and wires The plate generally follows the contour of the bottom surface of the object For the joystick, the base plate itself is a flat trapezoid with rounded corners A shallow rounded pocket will thus be drawn in the next few images to accommodate the plate This task begins in Figure 3.11 First, the straight lines of a trapezoid are drawn that remain equidistant from the outside edges of the bottom These will then be connected, next rounded, and then copied and repeated for the depth of the cavity In the first construction step, the line i is drawn parallel to the base, at a small distance w in the y direction from a, This line travels some distance past the outline 3.8 First Tutorial: Wire Frame 95 Construction