The present invention generally relates to nanoscale wires, and to methods of producing nanoscale wires. In some aspects, the nanoscale wires are nanowires comprising a core which is continuous and a shell which may be continuous or discontinuous, and/or may have regions having different cross-sectional areas. In some embodiments, the shell regions are produced by passing the shell material (or a precursor thereof) over a core nanoscale wire under conditions in which Plateau-Raleigh crystal growth occurs, which can lead to non-homogenous deposition of the shell material on different regions of the core. The core and the shell each independently may comprise semiconductors, and/or non-semiconductor materials such as semiconductor oxides, metals, polymers, or the like. Other embodiments are generally directed to systems and methods of making or using such nanoscale wires, devices containing such nanoscale wires, or the like.