In the sketching process, use an HB pencil on the cardboard, once I have the design, take the carbon pencil to mark the shadow places, with the fingertip I began to blur on the contour to check the lines and begin to give it depth and contrast to the design, after having the excess points, depth and density, take the rubber pencil "Faber Castell" to make the lighting effects in the design, the result is the following.