Methods, systems, and devices are described for slicing and shaping materials using magnetically guided chemical etching. In one aspect, a method includes forming a pattern on a substrate by a mask, depositing a catalytic etcher layer on the patterned substrate, a magnetic guide layer on the etcher layer, and a protection layer on the guide layer, etching the substrate by applying an etching solution to the substrate that chemically reacts with the etcher layer and etches material from the substrate at exposed regions not covered by the mask, steering the composite etching structure into the substrate during the etching by an applied magnetic field that creates a force on the guide layer to direct the etching, in which the steering defines the shape of the sliced regions of the etched substrate, and removing the etched material, the mask, and the composite etching structure to produce a sliced material structure.