M3-CRETE — Experimental Open-Hardware Concrete/Paste Printing Reference
A meter-scale cartesian motion reference for qualified technical teams working
with cementitious material extrusion in controlled R&D, laboratory, or
supervised institutional settings.
M3-CRETE is an experimental open-hardware reference design, not a consumer
product, hobby kit, finished machine, certified construction printer, or
structural concrete production system.
Read first:
The public release is limited to mechanical design information, low-voltage
control-interface references, and software/firmware references where published.
It does not include AC mains wiring instructions, control-panel build
instructions, facility-connection instructions, safety-rated emergency-stop
circuit designs, 48 V high-current distribution design, or code-compliance
instructions.
M³ = Mobile · Modular · Meter³
Developed by Sunnyday Technologies.
Current reference CAD — 2026-10-22
The full M3-2 STEP
retains 158 occurrences and 32 V-wheels, with eight wheels on the dual-plate
X carriage. The owner-approved reference placement and bounded software checks
are documented in the placement review.
See the assembly ISO and
ghosted lead-screw view.
The full STEP and renders still use the older boxed Z motor mounts. The
newer owner-supplied open-access STL
is a separate revision; a matching STEP, reviewed placement and physical fit
are still needed. Read the mount revision notes
before fabrication. Customizable BOM v2.19
links both revisions while preserving purchasing quantities and model defaults.
Reference placement approval does not establish manufacturing or physical validation.
| Spec |
Value |
| Open BOM component target |
Under $5,000 for public mechanical/low-voltage reference components where current commodity pricing and substitutions allow; professional electrical/power-control scope is excluded |
| Configured design envelope |
Default M3-2 target: 2000 × 1000 × 1000 mm. The assembled external footprint and shipping configuration have not been physically verified here. |
| Printhead weight |
~1.5 kg |
| License |
CERN-OHL-W-2.0 |
Why M3-CRETE
Most concrete 3D printers are either proprietary industrial systems or one-off
research machines tied to specific institutions. M3-CRETE targets the space
between: an open mechanical and controls reference that qualified teams can
study, adapt, and validate within their own controlled research or development
programs.
Target Applications
- Non-structural research specimens
- Process-development articles
- Digital formwork, molds, and fixtures
- Controlled materials and toolpath studies
- Laboratory and supervised institutional demonstrations
- Non-structural prototype objects where separately reviewed
Printed outputs require separate physical validation. No printed output from an
M3-CRETE-derived system may be used for structural, load-bearing, life-safety,
building-code, transportation, water-control, pressure-containing, occupied,
public-access, or permanent construction use unless separately designed, tested,
permitted, and approved by the responsible licensed professionals and
authorities for that specific project.
Design Principles
Mechanical Rigidity, Serviceability
The frame is engineered closer to CNC machine standards than desktop 3D
printers: rigid, durable, and precise. Mechanical components use standard
aluminum extrusions and commodity hardware where practical, so qualified teams
can inspect, replace, and modify parts without single-source dependency.
Lower Moving Mass, Still Hazardous
The current drive system is sized for the reference geometry using project
calculations and component assumptions that still require physical commissioning
and load validation. This does not make the machine safety-rated or safe for
unsupervised use. Moving axes, pinch/crush hazards, cementitious materials,
pressurized hoses, electrical systems, and software-controlled motion all
require qualified review, guarding, PPE, training, and operating procedures.
No Thermoplastic Melt System
Cementitious materials harden through hydration rather than thermoplastic melting and cooling, so the reference design does not use an FDM-style heated bed, hot end, or part-cooling system. That removes one class of hardware, but this repository does not establish a quantified cost, energy, or reliability advantage over other printer architectures.
Designed for Research Iteration
Some non-structural components such as brackets, guides, and enclosure parts are
designed to be 3D-printable. Those printed parts still require inspection,
material selection, and project-specific validation before use in a working
machine.
Firmware and Software Compatibility
M3-CRETE runs on established open-source toolchains. No proprietary software required.
| Layer |
Compatible Tools |
| Firmware |
Marlin, Klipper |
| Slicers |
Cura, OrcaSlicer, PrusaSlicer |
| Controls |
Standard stepper drivers, common control boards |
| CAD/CAM |
Any tool that exports STL, OBJ, or 3MF |
Standard G-code workflows provide full, transparent control over toolpaths, layer heights, and extrusion parameters.
Firmware configurations are maintained separately:
M3-CRETE-FIRMWARE
Repository Structure
M3-CRETE/
├── CAD/
│ ├── M3-2_Assembly.step # Development STEP assembly snapshot via LFS
│ ├── m3_2_assembly.py # CadQuery assembly generator (source of truth)
│ ├── self_check.py # 5-gate automated validation harness
│ ├── kinematics_eval.py # Structural analysis (deflection, torque, belts)
│ ├── Custom/ # 3D-printable brackets (STEP + STL)
│ ├── Components/ # OpenBuilds parts library (CC BY-SA 4.0)
│ └── Advanced/ # Extended parts (C-beam, joining plates)
├── bom/
│ ├── data.json # BOM source of truth (v2.7.0; 65 reference entries)
│ └── index.html # Interactive BOM viewer (bom.m3-crete.com/bom)
├── firmware/ # Reference Klipper config (machine config: M3-CRETE-FIRMWARE)
├── blog/ # Build logs and project updates
└── config.js # Model variants (M3-1, M3-2)
AI-Assisted CAD Workflow
This project uses CADCLAW, an automated checking framework for STEP CAD developed during this project. A declarative assembly spec places authored STEP parts by connector frames and datum chains, while software checks inspect selected inventory, interference, adjacency, dimensional, orientation, and floating-part rules. CADCLAW places parts authored in native CAD; it does not generate geometry. These checks are bounded software evidence, not proof of manufacturability, structural performance, tolerance compliance, safety, or physical fit.
See the CADCLAW repo for the generalized, reusable framework.
Material Compatibility
M3-CRETE is a hardware reference, not a materials approval. It does not
prescribe a construction mix, validate printed outputs, or certify any
cementitious formulation for field use. Mixes, toolpaths, curing, durability,
and acceptance criteria require separate physical testing and professional
review for each use case.
For early-stage materials-evidence and mix-design decision support, see
CEMFORGE. Where sufficient source
evidence exists, it can help organize candidate formulations for review; it does
not establish a mix’s performance or fitness. Every candidate requires physical
testing, provenance review, and qualified approval before project use.
Project Status
M3-CRETE is in active development. Current focus areas:
- Finalizing the open BOM and build documentation
- Validating open assembly notes and build sequence
- Establishing firmware profiles for concrete-specific extrusion parameters
Interested in contributing design feedback, supplier corrections, or controlled
build notes?
Open an issue or start a GitHub discussion.
Disclaimer
M3-CRETE is provided as-is for experimental, educational, and development
purposes. Concrete/paste printing involves moving machinery, cementitious
materials, pressurized material handling, and electrical systems that pose real
safety risks. Users assume all responsibility for safe design, construction,
commissioning, guarding, training, inspection, and operation of any system built
from these files.
Electrical / AC Mains Boundary
Any AC mains wiring, control-box integration, grounding, bonding, overcurrent
protection, disconnects, emergency-stop power circuits, facility connection,
inspection, or code compliance work must be performed by qualified personnel, a
licensed electrician where required, or a qualified control-panel shop.
The public M3-CRETE files may identify electrical interfaces, low-voltage
controls, and component references, but they are not AC mains wiring
instructions, control-panel build instructions, or a substitute for applicable
electrical codes, authority-having-jurisdiction review, or professional
electrical judgment.
See SAFETY_NOTICE.md,
ELECTRICAL_SCOPE_BOUNDARY.md, and
DISCLAIMER.md for full details.
License
This project is licensed under the CERN Open Hardware Licence Version 2 — Weakly Reciprocal (CERN-OHL-W-2.0).
You may use, modify, and distribute this design under the terms of that license. Modifications to covered files must be made available under the same license. This project includes no warranty of any kind.
Dual License Notice: V-Slot component CAD models in CAD/Components/ are based on OpenBuilds designs and are licensed under CC BY-SA 4.0. All other project files (custom parts, BOM viewer, firmware configs, documentation) are licensed under CERN-OHL-W-2.0.
See LICENSES/ for full license texts.
| Resource |
Description |
| Convergence Engineering whitepaper |
Methodology paper that uses M3-CRETE as a public case study; introduces the time to silence metric. CC BY 4.0 preprint, Zenodo. |
| Sunnyday Technologies |
Parent company — concrete 3D printing and engineered cementitious composites |
| M3-CRETE Project Page |
Hosted project overview and Sunnyday contact path |
| CADCLAW |
Automated STEP assembly compilation and validation, extracted from this project |
| CEMFORGE™ |
AI-powered concrete formulation platform by Sunnyday Technologies |
| M3-CRETE Firmware |
Firmware configurations for Klipper |
Author
Nicholas Sonnentag (ORCID 0009-0002-1897-384X) — mechanical engineer, founder of Sunnyday Technologies. M3-CRETE is designed and maintained by Nick; CAD iteration is LLM-assisted but the engineering judgment, component selection, build decisions, and direction are his.
Citation
If you use M3-CRETE designs in research, a controlled build, or derivative
work, please cite:
Sonnentag, N. (2026). M3-CRETE: Open-Source Concrete 3D Printer.
Sunnyday Technologies.
https://doi.org/10.5281/zenodo.19647435
For the methodology paper that uses M3-CRETE as a public case study, cite:
Sonnentag, N. (2026). Convergence Engineering: Commissioning Autonomous
Software by Measuring the Rate at Which Novel Failures Trend Toward Zero.
Sunnyday Technologies. https://doi.org/10.5281/zenodo.19863080
A CITATION.cff file is included for automated citation tooling.
Contributing
We welcome issues, pull requests, and design feedback from qualified teams. If
you are working with cementitious extrusion in a controlled technical setting,
your experience is valuable — open an issue or start a
discussion.
Contact: [email protected]
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