Fig. 4 shows two sketches of the same mobile phone stand. Sketch A is a 2D front view and sketch B is a 3D view drawn using crating. It works in rain and su...

(a) Crating is a sketching technique where a three-dimensional box (rectangular frame) is drawn first as a guide, and the shape of the product is then constructed within it [1]. The box provides the correct proportions of width, height, and depth, ensuring that the final sketch has accurate overall dimensions and a realistic sense of three-dimensional form. Details and curves are added once the outer box establishes the boundaries.

(b) A 3D sketch is more useful than a 2D sketch when presenting a design idea to a client because:

1. A 3D sketch shows the product from multiple faces, giving a realistic sense of depth, width, and height in a single view [1]. This allows the client to understand the overall form and spatial relationships immediately.
2. This helps the client visualise the finished product more clearly than a flat 2D drawing, making it easier to provide informed feedback on proportions, shape, and appearance [1]. A 2D front view alone cannot convey depth, surface curvature, or how different faces relate to each other, which can lead to misunderstandings about the designer's intent.

(c) When applying shading to sketch B with a light source coming from the upper left:

1. The top face, which faces toward the light source, would receive the lightest shading or be left white, as it catches the most direct light [1].
2. The right side face would have medium shading, as it is angled away from the light and receives less illumination. The front face would receive the darkest shading, as it is turned furthest from the upper-left light source and is in shadow [1]. This graduated change in tone across the three visible faces creates a convincing sense of three-dimensional form and volume.