  Lattice defects play a key role in determining the properties of crystalline
materials. Probing the 3D lattice strains that govern their interactions
remains a challenge. Bragg Coherent Diffraction Imaging (BCDI) allows strain to
be measured with nano-scale 3D resolution. However, it is currently limited to
materials that form micro-crystals. Here we introduce a new technique that
allows the manufacture of BCDI samples from bulk materials. Using tungsten as
an example, we show that focussed ion beam (FIB) machining can be used to
extract, from macroscopic crystals, micron-sized BCDI samples containing
specific pre-selected defects. To interpret the experimental data, we develop a
new displacement-gradient-based analysis for multi-reflection BCDI. This allows
accurate recovery of the full lattice strain tensor from samples containing
multiple dislocations. These new capabilities open the door to BCDI as a
microscopy tool for studying complex real-world materials.
