This tutorial review highlights the progress made during recent years in the development of the shell cross-linked (SCL) polymer nanocapsules and the impact of the most important scientific ideas on this field of knowledge. More precisely, it provides some guidelines towards the innovative design of SCL polymer capsules and presents different methods that have been used so far. It also includes the discussion on the major topics of stimuli-responsive moieties incorporated into spherical hollow polymer nanostructures. A wide variety of light and pH-responsive compounds together with synthetic strategies which enable introducing them in defined locations of macromolecular architectures are illustrated in this article. Moreover, this tutorial explains diverse methodologies for classifying the manifold formations of vesicular systems that allow for the preparation of SCL polymer capsules based on the general approach concerning the organization of polymers into well-defined vesicular assemblies followed by stabilization through covalent cross-linking.