A novel freeform 3D micro-fabrication technology, Projection Micro-StereoLithography (PµSL), is capable of rapidly fabricating highly complex 3D microstructures in a layer-by-layer fashion. PµSL utilizes the most advanced digital micro display technology as a dynamic mask generator, which works as a virtual photomask with digitally and dynamically configured patterns. This technique combines advantages of conventional stereolithography (SLA) and projection lithography, allowing for rapid photo-polymerization of the entire layer with a flash of UV illumination at micro scale resolution. Also, as a digital dynamic mask can control light intensity at a single pixel level, crosslinking density, thus material properties, of the fabricated structure can be tailored with desired spatial distribution. Furthermore, materials can be easily switched during the fabrication process, which enables heterogeneous integration of multiple functional material elements in a single process. Wide variety of functional material sets are available including polymers, responsive hydrogels, shape memory polymers, bio-materials.