  Macroscopic elastic core-shell systems can be generated as toy models to be
deformed and haptically studied by hand. On the mesoscale, colloidal core-shell
particles and microgels are fabricated and investigated by different types of
microscopy. We analyse, using linear elasticity theory, the response of
spherical core-shell systems under the influence of a line density of force
that is oriented radially and acts along the equator of the outer surface.
Interestingly, deformational coupling of the shell to the core can determine
the resulting overall appearance in response to the forces. We address various
combinations of radii, stiffness, and Poisson ratio of core and shell and
illustrate the resulting deformations. Macroscopically, the situation could be
realized by wrapping a cord around the equator of a macroscopic model system
and pulling it tight. On the mesoscale, colloidal microgel particles
symmetrically confined to the interface between two immiscible fluids are
pulled radially outward by surface tension.
