  The mechanical response of almost pure single-crystal micro-pillars under
compression exhibits a highly localized behavior that can endanger the
structural stability of a sample. Recent experiments revealed that the
mechanical response of a crystal is very sensitive to both the presence of a
quenched disorder in the sample and the orientation of the crystal. In this
work, we study the influence of disorder and crystal orientation on the large
strain response of a 2D FCC crystal with three active glide planes using a very
simple Eulerian plasticity model in the FE framework. Our numerical and
theoretical results on clean crystal pillars suggest that a single plane or
many gliding planes can be activated depending on the crystal orientation.
While in the former case, the deformation is localized, leading to ductile
rupture, in the latter, a complex interplay between active planes takes place,
resulting in a more uniform deformation. The strain-localization can be avoided
when inhomogeneities are engineered inside the crystal, or the crystal
orientation is altered because of the activation of multiple slip systems,
resulting in a "patchwork" of the distribution of the slip systems.
