A particular problem in this stage of modeling is to create a inner shell for the shell that's already modeled with subdiv. This portion is not visually complex but took quite some time to do. Directly calling solidify on this kind of surfaces will result in very long post-processing time and relatively bad surface quality for the inner shell as well as uneven thickness. Afterwards the remaining surfaces are all shelled out manually portions by portion and connected together afterwards, it then gave better result and saved more time.