Open-source RepRapMicron 3D printer fabricates at micron scale using common materials

The RepRapMicron project has published an open-source design for a 3D printer that works at the micron scale and is built largely from materials a hobbyist can obtain off the shelf. According to the project's GitHub wiki, hosted under developer Vik Olliver's account and surfaced on Hacker News's front page, the current recommended build, known as PIKA V0.02, delivers repeatable positioning of approximately 1µm and holds 10µm accuracy or better within a working volume roughly 8mm on a side.

What the current build achieves

The documentation lists concrete demonstrations. Using a fine probe that the machine etched for itself, the PIKA has deposited UV resin droplets as small as 4µm, and with a fibre-optic probe it has cured resin lines 9µm wide. It has printed a 0.5mm-long "Benchy" test model at 4µm layer height, and earlier experiments included mechanically etching a 1.3mm "Hello World" into Sharpie marker ink on a glass slide. The PIKA V0.02 hardware was completed around May 2026.

An earlier design, MAUS, is now deprecated. It served as a testbed for the flexure components and reached about 5µm positioning at best over a 4mm square, though the project notes its motion was not linear. Full build instructions, a bill of materials and pre-built STL files remain published for the MAUS C variant, with day-to-day progress logged on the RepRap blog.

How it works

The machine's precision has a clear lineage: the design builds on 3D-printed microscope platforms from the OpenFlexure Project, whose printed flexure mechanisms reach sub-micron resolution. At heart, the wiki describes the µRepRap as a very precise, compact CNC machine.

Each axis is driven by a 400-step NEMA17 stepper motor, with 200-step motors coming quite close to 1µm. Control is deliberately conventional — G-code over a serial connection, with Arduino running GRBL described as adequate. Two USB microscopes (8 megapixels or better recommended) handle Z-probe height and XY positioning during setup, while a conventional bench microscope at 100x to 200x magnification is used to examine the output.

The probe is the multipurpose core of the system, serving as Z touch sensor, engraving tool and deposition head. For rough work it can be a 0.5mm hypodermic needle or 0.25mm acupuncture needle used subtractively on surfaces such as marker-coated glass. Finer deposition calls for an electrochemically etched wire point — and the PIKA can fabricate those probes itself, a nod to the RepRap project's self-replication ambitions.

Additive fabrication currently works by dipping the probe into a smeared layer of UV nail gel resin, which the tip picks up by capillary action and deposits as fairly consistent droplets, with sizes under 15µm possible. A UV LED in the print bed cures the resin, which matters because thin resin layers exposed to air do not set properly — oxygen neutralises the activated photoinitiator. Alternatively, a 125/9 optical fibre paired with a 3W UV LED module can act as a print head that cures resin directly. Other substances can be transferred so long as their solvent does not evaporate during deposition, and materials that adhere to partially cured resin, such as gold leaf, can be added.

A RepRap for the very small

The project frames its goal historically. Precision manufacturing dates back to the 1700s, and the first micron-scale electronic devices were made from silicon in the 1960s — the Intel 4004, for instance, carried 10µm features. Since then, fabrication systems have become increasingly complicated, costly and, in some cases, dangerous for an amateur to handle, while the micron-scale measurement and manipulation tools common in biology and medicine tend to be big, purpose-built and expensive.

The µRepRap's stated objective has two parts: build a macro-scale, 3D-printed system for micron fabrication and manipulation, and along the way develop the techniques needed to reproduce a similar system printed at micron scale. Beyond the familiar printer requirements — three-axis positioning, CAD/CAM software, zeroing sensors, deposition and material — the wiki notes that humans cannot directly handle micron-scale assemblies, so new mechanisms are needed to detach, transport, rotate, maintain and interface with printed items.

What remains open

The documentation is candid about the limits. Much is still unknown about which objects can be printed and in which materials, and genuinely three-dimensional parts will require work on achievable height, overhangs, and printed hinges, flexures and folded structures.

Why it matters

If micron-scale manufacturing can follow the path RepRap opened for desktop 3D printing, several fields stand to gain. Biological sciences could get inexpensive, rapidly evolving equipment. Microelectronics could see independent communities building at micron scale again, loosening the field's reliance on silicon and on capital-intensive fabs. As with 3D printing, the project predicts applications in fields that do not yet exist. And a machine that etches its own probes plants the seed of the project's longer-term intent: replication at progressively smaller scales.