What is it?

The Monome Arc Clone - Ultra-Thin 12.5mm Edition is a meticulously engineered replica of monome's arc controller, available in both Arc2 (two-knob) and Arc4 (four-knob) configurations. Each knob features a high-precision encoder with 64 discrete steps per revolution, perfectly aligned with the 64-segment RGB LED ring that provides visual feedback. The knobs support push-button functionality, replicating the original flagship version's behavior for Max/MSP applications. Encased in a premium 3D-printed shell using Kexcelled art filament with a metallic finish, the controller measures just 12.5mm thick (9mm middle frame)—a significant reduction from the original's 1.5" (38mm) height. Connectivity is provided via modern USB-C interface, and each unit carries an independent serial number for authenticity. The device is fully compatible with the monome ecosystem, including norns (monome's sound computer), serialosc on Windows/Mac, and Max/MSP patches. A forthcoming firmware update will enable iii system support, allowing the arc to function as a standalone USB-MIDI controller with Lua scripting capabilities.

Why did you make it?

This project originated alongside our Grid clone development in July, with the vision of creating the most complete and aesthetically refined Arc replica available. We observed that existing clones suffered from three critical limitations: excessive thickness, inconsistent norns compatibility, and hardware quirks inherited from early open-source designs. While most DIY monome controllers work adequately with Max/MSP, they are "officially unsupported" for norns and require hacking the C codebase to function. Driven by dissatisfaction with these compromises, we undertook a complete redesign—rewriting the firmware from scratch and redesigning the PCB layout. The development process spanned six months, addressing unexpected challenges such as the unique handshake protocol between Arc and norns, optimizing encoder acceleration data handling, and ensuring stable high-refresh-rate performance without latency. We also resolved hardware issues like non-functional USB expansion ports found in the original open-source files. The result is a controller that not only matches the original's tactile precision but surpasses it in portability and ecosystem integration.

What makes it special?

Unprecedented Thinness & Integration: At 12.5mm total thickness, this is likely the slimmest Arc clone available, designed to pair seamlessly with our Grid clone for a unified monome experience. The custom 3D-printed case maintains structural rigidity while preserving access to all Raspberry Pi ports when used with norns shield setups. Norns Compatibility: Unlike most DIY clones that struggle with norns integration, our Arc clone achieves full compatibility out-of-the-box. This is a significant breakthrough, as norns scripts frequently assume arc connectivity for parameter control and sequencing. Future-Proof iii Support: The 2025 monome iii system represents a paradigm shift, enabling Lua scripting directly on the device with USB-MIDI enumeration. Our hardware is ready for this upgrade, allowing your arc to function as a standalone MIDI controller without a host computer—something even original pre-2025 arcs cannot do. Premium Build Quality: From the metallic-finish Kexcelled filament to the optional aluminum version, every component reflects boutique craftsmanship. The RGB LED rings offer multi-color adjustability, simulating official yellow and white editions while supporting custom colors like green to match norns screen aesthetics. Each LED is carefully selected (costing nearly 2 RMB each) for consistent brightness and color accuracy, with a sophisticated diffusion stack including light shields, reflection layers, and frosted acrylic. Engineering Excellence: We custom-designed ultra-thin high-resolution encoders in partnership with manufacturers, hand-selecting each unit for precision. The Arc4 model includes 256 RGB LEDs—equivalent to a full-sized monome Grid 256—requiring meticulous assembly with multiple 3D-printed diffusion layers and manual quality control. The addition of a 3D-printed screen bracket ensures stable display alignment, while laser-etched inner back panel text eliminates the frustration of hunting for I/O ports. Ecosystem & Support: The controller works flawlessly with serialosc on Windows/Mac, norns, and VCV Rack's Ansible module. We provide long-term firmware support with regular updates based on community feedback. Recent improvements include a custom power cable for Arc4 to resolve power delivery issues, and optional tilt stands for ergonomic use. Each unit ships with a unique serial number and the promise of continuous refinement, ensuring your investment remains relevant as the monome ecosystem evolves.