The modeling steps we've already been through can be leveraged further to add more fine detail to the model, but to demonstrate this all the way through to complete realization of the design drawing would take many more pages of rather similar operations. Instead, it would be more instructive to show a few features of a sculpting workflow, which can be used to obtain detail from a high-resolution model for texture mapping onto a low-resolution model.
The steps for sculpting an existing model begins with creating texture co-ordinates.
UV mapping (texture co-ordinates) flatten the model's 3D polygons into a flat square. U refers to horizontal texture space, and V refers to vertical texture space. This space easily matches the width and height of a Photoshop document. The classic concept of UV mapping is to imagine the surface of a dice (3D) being unfolded into a single flat surface (2D), so each facet can be painted with unique features. Details of the Unwrap...