EVOLUTION OF 3D IMAGE
Step 3: Create the solid model
Using the wireframe model as a background, solid forms and planes are "constructed" by "tracing" over the appropriate lines in the wireframe. By selecting certain commands, the user can inform the program that the form about to be drawn is a solid and not, for example, a cube formed by a wire frame placed around its edges (hence the name, "wireframe").
The model can then be "shaded" by the program. That gives form to the solids. In that way the model can be evaluated for the degree to which the forms accurately reflect the designed object. Colors are arbitrary at this point, and are used chiefly by the designer to keep track of which lines belong to each material or assembly.
This model was created using DesignCAD 3D v4 for DOS
Next - Rendering the Model.