Daily Practice
After have studied the internal components or had a clear idea of the volumes or structure frame a product needed, the approach of use planes to visualize the mass of the product is useful at an early stage of design. Create different planes, ground plane, middle plane, cross-section would help to think and visualize three dimensionally. Use reference planes make it easier to develop and refine the mass.
Objective
As a preliminary sketching practice, define the basic planes first, outline the profile for each planes, constantly adjust the profile or contour lines during the process to explore the difference of the overall forms.