First, we will work on the front of the model, starting where we left off in the last chapter. For almost the entire model, we will use the edge modeling technique to create the spacecraft for better control of the topology of the model. If you don't remember the basis for this technique, all we have to do is select an element of the mesh, such as a vertex, edge, or face, with the extrude tool and create new parts of the model. In this project, the snapping tools of Blender will be very important to build the model with the minimum of precision.
Take the model finished in the last chapter, and in the edit mode, select the edge pointed in the following image:
With the edge selected, press the E key to create an extrusion. Right after the extrusion, move the new edge down a bit. When the new edge is placed, press the E key again to create another extrusion and move it down as well, until the new faces look like the ones displayed in the following image...