Polymer 3D printing is an emerging technology with recent research translating towards increased use in diverse industries. The polymer 3D printing process works by depositing a polymer in a directed fashion to form a completed part, generally through layer by layer deposition.  Polymer printing is advantageous because it enables printing low-cost functional parts with diverse properties and capabilities. An important aspect polymer 3D printing is the consideration of materials, processes, and design strategies that all influence a parts performance. Research in materials has led to the development of polymers with advantageous characteristics for mechanics and biocompatibility, with tuning of mechanical properties achieved by altering printing process parameters. Suitable polymer printing processes include extrusion, resin, and powder 3D printing, which enable directed material deposition for the design of advantageous and customized architectures.  Through careful consideration of material, process, and design it is possible to create a 3D printed polymer part of complex geometry that is tuned for a specific application on a per-print basis.