The objective of this PhD thesis is to investigate the potential application scenarios for polymer-based 3-D printed metal-pipe rectangular waveguide components. For all 3-D printing, masked stereolithography apparatus (MSLA) technology is used for demonstrating millimeter-wave (30 to 300 GHz) and terahertz (300 GHz to 3 THz) waveguide components. In Chapter 1, an overview of three general manufacturing categories (i.e., formative, subtractive and additive manufacturing) is first given. Various types of polymer-based 3-D printing technologies are then introduced in details. Finally, 3-D printing procedure including preparation and post-processing is presented. Chapter 2 gives an overview of millimeter-wave (mm-wave) and terahertz (THz) 3-D printed metal-pipe rectangular waveguide (MPRWG) components. A detailed literature survey associated with this PhD work is given. In Chapter 3, quantization properties associated with a pixel-based MSLA 3-D printer have been characterized. In order to verify the proposed predistortion methodology, 5th order G-band chained-function filters without and with predistortion are designed, manufactured and measured. Chapter 4 demonstrates polymer-based 3-D printed waveguide thru line, single-cavity resonators and bandpass filters at WR-2.2 band. An RLC equivalent circuit model is used to characterize the single-cavity resonators without and with corner rounding compensation (CRC). For the first time, polymer-based 3-D printed terahertz filters have been successfully demonstrated. Chapter 5 demonstrates W-band waveguide thru line and twist with integrated filtering. For the first time, rotational electromagnetic bandgap (EBG) structures are used to realize the integrated filtering function instead of employing conventional irises and septa. Chapter 6 demonstrates the proof-of-concept for 3-D printed waveguide-to-chip interconnects. Two on-chip Vivaldi antennas are used to realize the electromagnetic-field coupling between a 3-D printed host MPRWG and its packaged D-band RFIC thru line.