UNIT - Universal Network of Interchangeable Toolholders (Parametric, OpenGrid Compatible)

The Universal Interchangeable Network of Toolholders —a robust, standardized, and fully parametric tool organization ecosystem for workshops, maker spaces, and garages. 

I started with french cleats. Most French cleat models available online suffer from two key problems: 1. They integrate the cleat directly into the tool holder, forcing awkward print orientations that lead to weak layer lines across the load-bearing cleat bevel, or lots of supports. 2. Friction-fit slide connections frequently bind or jam when printed across different machines and tolerances.

This system solves both issues by utilizing a two-part modular design: Mounts that print on their sides with continuous filament strands running along the load-bearing 45° bevel, maximizing shear strength. Different mounts are available for french cleats and multiconnect, and more options under development. Tool Holders: Fasten securely to mounts using standard M3 machine screws into standard M3 hex nuts. Trapezoidal Locking Grooves: Self-aligning 45° angled grooves lock the backplate firmly against the cleats, eliminating wobble, rotation, and sagging even under heavy loads. 28 mm Grid Standard: Built upon the 28 mm pitch shared with OpenGrid (by David D) and relatively compatible with Gridfinity (by Zack Freedman).

IMPORTANT: French Cleat Rail Height

The pre-rendered STL and STEP files provided in this release are dimensioned specifically for French cleat wall strips that are 73 mm (approx. 2-7/8”) high, with a standard 45° top bevel and nominal 19 mm (3/4”) thickness. They also assume M3 hardware.

If your workshop French cleat rails are any height other than 73 mm:

1. Use the models here without the bottom cleat. All the weight is on the top cleat. The bottom cleat is just there to improve retention on the wall cleat.

2. Custom Generation via GitHub:
   Visit the repository at https://github.com/atiretoo/french_cleats. The entire ecosystem is generated programmatically using Python and CadQuery. You can simply specify your rail height (e.g. --rail-height 65.0 or --rail-height 89.0) and generate perfectly customized cleats and tool holders for your exact walls in seconds. Change the hardware to M4!

3. Message Me:
   You can send me a message here on Printables with your cleat dimensions. I will do my best to render and upload models for other rail sizes, hardware, or tool dimensions when time permits, but please be aware that responses may be slow.
   

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Recommended Print Settings

All exported STL models have been audited and pre-oriented for optimal slicing:

•     Print Orientations and settings:

–    Braced Holders (Slot, Screwdriver, Chisel, V-Holder): Pre-rotated to print flat on their side with the support gusset resting on the build plate. This ensures continuous, uninterrupted extrusion across the shelf cantilever with zero supports required.

–    Hook Holder & Gridfinity Shelves: Pre-rotated to print flat on their backplates.

–    Cleats: Pre-rotated to print on their side faces, providing maximum layer strength across the 45° cleat bevel.

•     Material: PETG, ABS, or ASA is strongly recommended for workshop longevity, creep resistance under load, and impact toughness. PLA is suitable for lighter hand tool organizers. My current testing is mostly Elegoo PETG and PLA printed on a Prusa Core One.

My test results used the following settings; these are not necessarily optimal. Further testing is underway.

•     Perimeters / Walls: 2 walls (approx. 1.6–2.0 mm wall thickness).

•     Top & Bottom Layers: 3 layers.

•     Infill: 15% (Grid).

•     Supports: None needed when using the default exported orientations.

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Hardware Required

•     Screws: M3 button head or socket head cap screws (M3 x 12 mm to M3 x 16 mm recommended).

•     Nuts: Standard M3 hex nuts (DIN 934 / ISO 4032, 5.5 mm across flats, 2.4 mm thick).

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Attributions & Sources of Inspiration

This project stands on the shoulders of giants. While designing this system, I built upon the brilliant work already done by many, synthesizing the best aspects of several existing systems into a unified standard:

•     Frenchfinity by Bastelsaal (frenchfinity.xyz): Inspired the excellent concept of separating the cleat base from the tool holder itself. Separating the components is what enables printing on edge for maximum layer-line shear strength across the 45° cleat bevel.

•     Screw & Ridge Locking Inspiration by shoooo (@shoooo_1013338 on Printables): Heavily inspired by shoooo’s clever use of registration ridges and screws. I standardized this concept into self-aligning trapezoidal grooves for rock-solid, repeatable locking.

•     OpenGrid by David D (Printables Model #1214361): Provided the 28 mm modular pitch standard adopted across all backplates, cleats, and adapters.

•     Gridfinity by Zack Freedman (YouTube): The gold standard for desktop and drawer organization, directly integrated into the French cleat shelf mounts.

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Source Code & CAD Files

•     GitHub Repository: https://github.com/atiretoo/french_cleats

•     STEP Files: Full STEP assemblies and individual component models are included in step_files.zip under the Other Files section for seamless remixing and CAD customization.

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AI Disclosure: The “Centaur” Approach

This project is developed using a collaborative human-AI workflow. The CadQuery Python code, geometric algorithms, refactoring, and documentation were written and refined with the assistance of advanced AI models.

I approach AI not as a tool for blind self-automation, but as a collaborative interaction. I aspire to be a centaur, maintaining structured and controlled interactions with AI, harnessing it as a tool for targeted efficiency. In this model, the AI acts as a high-powered pair-programming partner, helping me rapidly explore geometry, write parametric test suites, and audit dimensional consistency. Meanwhile, I hold the strategic architectural vision, conduct the physical slicing, 3D printing, and workshop validation, and apply and build domain knowledge throughout the process.