Microfluidics has rapidly advanced in the fields of chemical and biological research since 1980s due to its unique ability to make low-cost, high-throughput platforms. The most far-reaching breakthrough in microfluidics has been the development of soft-lithography using rigid micromachined molds to shape elastomeric polymers. Among polymeric materials, Polydimethylsiloxane (PDMS) is commonly used due to its numerous ideal properties, including its ease in manufacturing, reasonable cost, as well as strength, transparency, and especially biocompatibility. However, traditional PDMS methods for fabricating microfluidic devices have a unique set of challenges, including long and expensive process times, and feature sophistication limits (e.g. restricted to rectilinear features). To address these challenges, researchers at UC Berkeley have developed novel 3D printing techniques for fully-integrated, multi-layer microfluidic objects to achieve greater system-level functionalities. For demonstration, UC researchers created complex, high-quality geometries in PDMS without the need for a microscope, including thin membranes and rounded channels and while accounting for surface roughness. Their novel processes could enable assembly of microfluidic components into sophisticated 3D architectures, which may provide a new platform for rapidly creating complex microfluidic devices in volume.