To develop a structural sketch, you’ll use blocking-in, proportioning and aligning. You can then use the structural sketch as the foundation for a finished drawing.
Blocking-in involves sketching the general form of the subject through basic line and shape. You’ll increase accuracy throughout the process by proportioning and aligning along with structural details.
Start to block in the subject by sketching the overall form using the most obvious lines and shapes. Proportioning and aligning can be used to ensure the accurate placement of the features.
Develop the form by progressively adding smaller features. The proportions of the previous step must be accurate for the proper size and placement of these features.
Now add details to complete the structural sketch, which can be used as the foundation for a finished drawing.