  We explore the potential of 3D metal printing to realize complex conductive
terahertz devices. Factors impacting performance such as printing resolution,
surface roughness, oxidation, and material loss are investigated via
analytical, numerical, and experimental approaches. The high degree of control
offered by a 3D-printed topology is exploited to realize a zone plate operating
at 530 GHz. Reflection efficiency at this frequency is found to be over 90%.
The high-performance of this preliminary device suggest that 3D metal printing
can play a strong role in guided-wave and general beam control devices in the
terahertz range.
