Microscope projection lithography offers an affordable alternative for fast prototyping of 3D polymer microstructures. Here we introduce a 3D mask-less approach operating on a routine epi-fluorescene microscope that enables the fabrication of 3D microstructures such as lenses, pillar forests, cavities and channels embedded in a monolithic SU-8 structure defined in a single exposure step. Fabrication times of about 1 hour from design to finished structure are achieved and 5 mu m resolution is possible in the present configuration.