MPCNC Primo
The Mostly Printed CNC is the CNC router that 3D printing made possible — Ryan Zellars's design replaces a welded steel frame with printed plastic joints, routes standard EMT conduit through them, drops a commodity ESP32 controller underneath, and puts the whole thing under a permissive open licence. No cloud, no subscription, no proprietary board. The most open desktop CNC on this list.
If you own a 3D printer and want a CNC router that costs under $600 for a complete build, touches no closed hardware, needs no cloud account, and is documented down to the machine-config level, the MPCNC Primo is the clear answer. The honest constraints are rigidity — keep the X and Y axes under around 600 mm and you get reliable wood, plastics, and light aluminium; push further and the printed rails flex. It is not a production machine. It is the most open CNC router you can build.
What it is
The MPCNC Primo is a self-build CNC router designed by Ryan Zellars of V1 Engineering. The Primo (released around 2020) replaced the earlier Burly version and remains the current design as of 2026. The machine's defining trick is that its structural components — the corner pieces, gantry rails, and Z-axis core — are all 3D-printed. Standard EMT electrical conduit (~$12 for 20 feet at any hardware store) slides through the printed joints to form the linear motion system. A conventional spindle or router mounts in the Z-axis core.
Because the frame geometry is set by your tube lengths, the work area is entirely user-configurable. The practical ceiling — where printed-rail rigidity becomes limiting — is roughly 600 × 600 mm; beyond that, V1 Engineering recommend switching to their LowRider 4 design, which uses the same controller and firmware on a more rigid frame suited to larger sheets. The Primo is the compact, desktop option.
In addition to routing, the MPCNC accepts tool-head swaps: diode laser, drag-knife vinyl cutter, plasma torch, pen plotter. It is a platform, not a single-purpose router.
Openness
The MPCNC Primo scores very open across every dimension except one licence restriction on the part files themselves.
- STL files — CC-BY-NC-SA 4.0, open for use. The printed parts are published on GitHub under Creative Commons Attribution-NonCommercial-ShareAlike 4.0. The NonCommercial clause restricts selling the printed parts — Ryan Zellars reserves that for V1 Engineering's shop. But using the machine commercially — routing parts for clients, charging for machine time, running it in a business — is explicitly permitted. For a builder, the licence is effectively unrestricted.
- Firmware — FluidNC, GRBL-compatible, open. New builds use FluidNC (AGPL-3.0 configs), an ESP32-based GRBL-compatible firmware with a built-in Wi-Fi web UI. Configuration is a plain text file — no recompiling for parameter changes. V1 Engineering maintains an older Marlin fork for builders who already own SKR Pro or Rambo hardware; both paths are fully open-source.
- Controller — Jackpot3, GPLv3. The current recommended board is the Jackpot3 at $75.99: an ESP32-WROOM-32 module with six integrated TMC2226 stepper drivers, USB-C, Wi-Fi, Bluetooth LE, and an RJ11 expansion port. The board design is published under GPLv3. It is sold by V1 Engineering and by Elecrow — no single-source dependency. If you already own a BigTreeTech SKR Pro, Rambo, or RAMPS + Mega, the Marlin firmware path supports those boards without buying new hardware.
- Klipper — not applicable, but the equivalent is open. Klipper is 3D printer firmware. CNC routers use GRBL-family controllers. FluidNC is the Klipper analogue here: host-resident motion planning, text config, web UI, active open-source community. The MPCNC firmware story is as open as Klipper's.
- CAM and sender — fully open. V1 Engineering document ESTLCam as their first-choice CAM tool. The machine accepts standard GRBL G-code from Fusion 360, FreeCAD Path, Vectric, and any other tool with a GRBL post-processor. Laser work is natively LightBurn-compatible on the Jackpot3. G-code senders: CNCjs, Universal Gcode Sender, Repetier-Host, or the FluidNC built-in web UI. No account required for any of this.
- Ecosystem — no cloud, no subscription, self-sourceable. Every part of the build is self-sourceable: EMT conduit from a hardware store, printed joints from your printer or V1 Engineering's shop, commodity hardware from any fastener supplier, the Jackpot3 from V1E or Elecrow. The FluidNC web UI runs entirely on the ESP32 — no internet required during operation. Firmware configuration is a file you edit in a text editor.
AI tooling
There is none. The MPCNC's official toolchain — ESTLCam, FluidNC, the Jackpot3 — contains no AI features. No machine vision, no adaptive toolpathing, no LLM-assisted CAM.
The openness of the stack means you can add a camera for remote monitoring or build scripting around the G-code layer, but that is DIY work, not a product feature. For a machine at this price point and in this community, the absence of AI is unsurprising and not a meaningful gap.
Where it wins
- The most open desktop CNC router you can build. Open STLs, open firmware, GPLv3 controller, open CAM, no cloud. Nothing in the hobby CNC space beats this on pure openness.
- Genuinely self-sourceable. EMT conduit at any hardware store, printed joints from your own printer, Jackpot3 from V1E or Elecrow, commodity fasteners. No part is a proprietary consumable. If V1 Engineering disappeared, the build documentation, STL files, and FluidNC firmware exist independently.
- Multi-tool platform. Router, laser, vinyl cutter, plasma, pen plotter — swap the head, reload the config. The Jackpot3 supports laser PWM natively; LightBurn works out of the box.
- Active, detailed community. The V1 Engineering forum has years of build logs, troubleshooting, and config files. The documentation at docs.v1e.com covers assembly, firmware config, CAM workflow, and tool-specific setups.
- Low entry cost. A complete build — Jackpot3, kit hardware, printed parts, conduit — runs around $400–600. The controller is $75.99. The structural parts cost nothing if you print them yourself.
- FluidNC Wi-Fi web UI. Once configured, you send jobs from a browser over your local network. No USB cable required in normal operation, no software to install on the sending computer.
Where it's locked down
- Rigidity is the hard constraint. The printed plastic joints and conduit tubes flex under cutting load in a way that a steel-framed machine does not. The practical work area limit is around 600 × 600 mm; aggressive feeds in hardwood or aluminium need conservative passes. This is a physics limitation, not a software one — but it is the primary reason the MPCNC is not a production machine.
- CC-BY-NC-SA limits selling printed parts. You cannot sell the printed parts to others (outside a narrow exception in the V1E forum for single-machine sales). This only matters if you want to run a parts business — for personal builds and commercial use, the licence is unrestricted.
- Build kit currently on hold. As of 2026, V1 Engineering has paused the Primo hardware kit due to tariff-related pricing concerns, and recommends the LowRider 4 for many use cases. The STL files and controller are still available; self-sourcing the hardware is well-documented. The pause is a supply-chain issue, not an end-of-life signal.
- No official pre-built option. There is no "assembled MPCNC Primo" to buy — it is a self-build by design. If you want a machine you can use the day it arrives, look at the Shapeoko or CNC 3018 Pro.
- CAM learning curve. ESTLCam is well-documented in the V1E context, but any CAM tool involves setup time, especially for feeds-and-speeds on a machine with non-standard rigidity characteristics. The community forum is the resource here.
Who it's for
Makers who already own a 3D printer and want their second machine to cost as little as possible, touch no closed hardware, and be documented down to the machine-config level. The MPCNC Primo is the natural choice when the priority is openness over rigidity — and when the work area fits within the 600 × 600 mm sweet spot. It is also an excellent second machine for someone who already has a more rigid CNC (Shapeoko, Onefinity) and wants a low-stakes testbed for a laser head, plasma cutter, or drag knife.
If you need a larger work area or more rigidity, the LowRider 4 uses the same Jackpot3 controller and FluidNC firmware on a more rigid frame designed for sheet goods. If you want something you can buy assembled and use today, the Shapeoko 5.1 Pro or CNC 3018 Pro are the right comparisons.
Specs & links
- Design: MPCNC Primo — current version as of 2026. Tubing variants: 23.5 mm (C), 25 mm (F), 25.4 mm / 1 inch (J).
- Work area: User-defined by tube length. Practical limit ~600 × 600 × 80 mm. Standard kit belt yields ~780 mm combined X+Y workspace.
- Frame: 3D-printed joints + EMT electrical conduit (standard 3/4" or 1" size per variant). EMT ~$12 for 20 ft from any hardware store.
- Controller (recommended): Jackpot3 — ESP32-WROOM-32, 6× TMC2226, Wi-Fi, USB-C, GPLv3, $75.99. Also sold via Elecrow.
- Firmware: FluidNC 3.9.9 (AGPL-3.0 configs) — GRBL-compatible, built-in web UI. Legacy: Marlin for SKR Pro / Rambo / RAMPS boards.
- STL files: github.com/V1EngineeringInc/MPCNC_Primo — CC-BY-NC-SA 4.0.
- CAM: ESTLCam (recommended), Fusion 360, FreeCAD Path, Vectric; any GRBL-compatible post-processor.
- Laser: LightBurn-compatible on Jackpot3/FluidNC (PWM laser output).
- Build kit: V1 Engineering store — $242.99 for hardware (on hold as of 2026; controller separate).
- Complete build estimate: $400–600 (Jackpot3 + hardware kit + printed parts + conduit).
- Documentation: docs.v1e.com/mpcnc.
- Community: forum.v1e.com.