  In small volumes, sample dimensions are known to strongly influence
mechanical behavior, especially strength and crystal plasticity. This
correlation fades away at the so-called mesoscale, loosely defined at several
micrometers in both experiments and simulations. However, this picture depends
on the entanglement of the initial defect configuration. In this paper, we
study the effect of sample dimensions with a full control on dislocation
topology, through the use of a novel observable for dislocation ensembles, the
$\Lambda$-invariant, that depends only on mutual dislocation linking: It is
built on the natural vortex character of dislocations and it has a
continuum/discrete correspondence that may assist multiscale modeling
descriptions. We investigate arbitrarily complex initial dislocation
microstructures in sub-micron-sized pillars, using three-dimensional discrete
dislocation dynamics simulations for finite volumes. We demonstrate how to
engineer nanoscale dislocation ensembles that appear virtually independent from
sample dimensions, either by biased-random dislocation loop deposition or by
sequential mechanical loads of compression and torsion.
