RackStack: A Modular 3D Printable Mini Rack System with Slide-In Hex Nuts

If you've ever tried to organize a small home lab, a few Raspberry Pis, or a collection of mini PCs, you know the pain of finding a rack that fits. Most racks are either too big, too expensive, or not modular enough for the weird assortment of gear we accumulate. RackStack is a clever open source project that solves this with 3D printed parts and a simple but smart hardware trick.

What It Does

RackStack is a modular, 3D printable mini rack system. The core idea is that you print custom-sized rack "rails" and "shelves" that snap together using slide-in hex nuts and standard M3 bolts. Instead of needing a big metal rack or a whole custom enclosure, you can build exactly the rack you need for your specific devices — and scale it up later.

The repository provides STL files, OpenSCAD source files, and detailed instructions for printing and assembling the system. It's designed for standard 19-inch rack widths but can be scaled to any size you want.

Why It’s Cool

The standout feature here is the slide-in hex nut design. Instead of tapping plastic or using inserts, the rack rails have channels that let you slide a hex nut into place. Then you just screw in an M3 bolt from the other side. This makes assembly and reassembly trivial — no tools needed beyond a screwdriver.

Other smart bits:

• Parametric design — The OpenSCAD files let you tweak the width, depth, and hole spacing to fit your gear.
• Stackable modules — Each printed "unit" can be stacked vertically, so you can start with one shelf and add more as your hardware grows.
• No complicated hardware — Just your 3D printer, some M3 bolts, and standard hex nuts. No special rails, no oddball parts.
• Clean and sturdy — The prints are designed to look professional and hold up to real use, not just sit on a desk.

A great use case: you've got a Raspberry Pi, a USB hub, and a small switch that need to live together. Print a 1U shelf, slide in your hex nuts, mount the gear, and stack it. Done.

How to Try It

1. Grab the files — Head over to the RackStack GitHub repo and download the STLs or the OpenSCAD source.
2. Print the parts — You'll need a 3D printer that can handle about 200mm x 200mm build plate. The default 1U rail is around 190mm wide. Print in PLA or PETG — both work fine.
3. Get hardware — You'll need M3 bolts (8-12mm length works well) and standard M3 hex nuts. The system uses 4 bolts per shelf, plus extra for mounting your gear.
4. Assemble — Slide the hex nuts into the channels on the rail, line up your shelf, and screw in the bolts. You can stack multiple units by printing more rails and connecting them end-to-end.
5. Mount your gear — The shelves have slots for zip ties, or you can print custom mounting plates. The OpenSCAD source makes it easy to add your own holes.

No installation required — just print, slide, and screw.

Final Thoughts

RackStack is the kind of project that makes you wonder why no one thought of it sooner. It's simple, well-documented, and solves a real pain point for anyone with a growing collection of small electronics. The slide-in hex nut trick is especially elegant — no fumbling with nuts in tight spaces, no permanent adhesives.

If you're into home labs, 3D printing, or just like building custom enclosures for your gear, this is a solid weekend project. Even if you don't have a 19-inch rack, the parametric design means you can adapt it to any size. Highly recommend checking it out.

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