tl;dr: μRepRap is an open-source project to build a RepRap-style 3D printer capable of micron-scale fabrication using common materials, derived from OpenFlexure microscope designs. The current "PIKA" V0.02 build achieves ~1μm repeatable positioning in an 8mm cubic volume and can deposit 4μm UV resin droplets using an electrochemically etched probe as its print head. The goal is to democratize MEMS and microelectronics fabrication the way RepRap did for desktop 3D printing, with the eventual aim of self-replication at even smaller scales.