The experimental studies of spin-crossover compounds switched in the last decade from bulk measurements and macroscopic observations to the nanoscale and microscopic approaches. In this context, new and sometimes unexpected behaviours have been documented, which could be partially described only by the classical phenomenological models developed in the last period of the last century. In this context, the development of more complex models, able to reproduce the nucleation and domain propagation within the material, has proved to be not a whim of some theoreticians but a necessity, which facilitated the full understanding of observed phenomena and even made premises for further experiments. Here, we present and analyse various elastic models identifying their common points and differences and discuss how they can be used for the study of microscopic phenomena as the cluster formation, stability and propagation or for the study of finite size effects in spin-crossover nanoparticles, with open boundary conditions or embedded in various matrices.