Gridfinity storage: choosing grid units, bins and materials

What the 42 mm grid locks down and what it leaves open

Gridfinity started as a project by Zack Freedman. It has two basic parts: a baseplate and the blocks that sit in it. According to the unofficial specification on GitHub, the core of the design is a 42 x 42 x 7 mm grid format. Every block drops into a z-shaped socket cut into the baseplate. That socket lets you rearrange blocks freely while a vertical lip keeps them from sliding out.

The same document illustrates a generic single-unit block measuring 41.5 mm square to leave clearance inside the baseplate. That dimension describes the illustrated block: do not use it as a pitch to multiply when sizing a multi-unit bin. The grid pitch remains 42 mm; check the exact file's dimensions and clearance before printing.

The repository describes itself as unofficial; these documents do not certify the conformity of a chosen file. Variants exist, especially on the stacking lip and magnet holes. Before committing to a batch, open the source file you picked and check its dimensions instead of trusting the Gridfinity name alone.

Sizing a drawer: count grid units before you open the slicer

Start with the drawer, not the bin. Measure the usable inside width and depth, then divide each by 42 mm. The whole number you get is how many grid units the baseplate can hold in that direction. The remainder is lost space, which some people fill with a trimmed edge plate.

Baseplates then get split into pieces that fit your build volume. Compare the drawer's width and depth with the usable bed size on your printer's spec page: if the drawer exceeds that area, the baseplate becomes several segments laid side by side, each cut to a whole number of 42 mm units. Decide on that split before you open the slicer.

For height, the 7 mm step in the base format is the reference. The Stu142 documentation has a section explaining bin units and provides technical drawings from several viewpoints, specifically so you do not have to calculate dimensions yourself. A deep bin for drill bits and a shallow bin for driver tips have different heights, but both still stack if the lip follows one of the two documented profiles. If you want ideas beyond storage, our page on useful things to 3D print goes wider.

Magnets, screws and inserts: the hardware list to verify before ordering

A Gridfinity bin stays in its baseplate through geometry alone. Magnets are optional. According to the unofficial specification, they supplement the socket and hold blocks more reliably, which matters in a drawer you yank open. The format is a 6 mm diameter, 2 mm thick magnet. The document recommends holes in all four corners of every unit so the block stays compatible in any rotation.

The Stu142 documentation confirms this as the standard size in the Gridfinity ecosystem. It adds an alternative: M3 screws driven up from the bottom to secure the bin to the baseplate. The screw holes can also be widened to 4.2 mm in diameter to take M3 heat-set inserts, which it presents as a more secure attachment method.

So before you order, write a three-line bill of materials: 6 x 2 mm magnets, M3 screws, and M3 inserts if you want that option. If you follow the recommendation of holes in all four corners of every unit, count four magnets per grid unit, not per bin. A two-by-three bin therefore needs twenty-four. Because the specification presents magnets only as a supplement to the socket, decide bin by bin: reserve them for bins that must stay put under shocks, and let the rest rely on the socket alone.

Files, generators and licensing: where to start

Two GitHub repositories serve as the technical entry point. The first, the unofficial specification, sums up the concept in a few diagrams: block profile, labels, magnets, baseplates. The second, the Stu142 documentation, goes further with technical drawings in PDF and SVG, the bin base profile, corner radii, and both stacking lip variants. Its author notes that the rounded lip is not identical to the original models, but close and easier to recreate.

To generate your own bins without modeling, the same author offers a Gridfinity generator workbench for FreeCAD, installable from the built-in addon manager. It produces matching bins and baseplates with one click. The parametric files are published in a collection on Printables, and every drawing in the repository was made with FreeCAD.

Licensing is settled file by file. The Stu142 repository has a LICENSE file at its root. Read it before you reuse the drawings in a project, especially a commercial one. Models downloaded from a sharing platform carry their own license, which may differ from the documentation's. Our page on licenses and rights covers the common cases. Never assume a Gridfinity file is free to use just because the format is open.

PLA or PETG for workshop bins: what the datasheet says

Both materials work for storage bins. The choice depends on what goes in them and where the drawer lives. The Stu142 documentation lists Polymaker PETG and Polymaker PLA among its components without picking a winner.

The Prusament PETG datasheet gives concrete points. It describes a filament that is more heat resistant, more flexible and less brittle than PLA, with a stated temperature resistance of 68 °C, though the page does not state the test method. That figure is manufacturer data, not a guaranteed service temperature for a loaded bin. It rates printing difficulty as easy to medium, with low warping and strong layer adhesion. The listed applications include holders and clamps for a workroom, which is exactly what a bin is. For a drawer exposed to heat, that stated gap over PLA is an argument to confirm with a test bin placed in real conditions.

The same sheet lists the downsides. PETG tends to string, bridges poorly, and is not recommended for tiny parts. It sticks hard to the bed, so removal needs care. The listed settings are a bed at 80 ± 10 °C, a nozzle at 250 ± 10 °C and the part fan at 50 percent, with no enclosure required. For desk bins with no heat exposure, compare a trial bin in the material you already use. Our PLA vs PETG guide completes the decision for your machine.

Settings and budget for a batch of bins

A batch of bins is measured in hours and grams. Before you launch ten parts, print one single-unit bin and one single-unit baseplate, then check the fit and the stacking. That test costs little and exposes a misread dimension before the filament is gone.

For strength, the Prusament PETG datasheet recommends increasing the number of perimeters rather than the infill percentage, because most of a print's strength comes from its outer shell. On your trial bin, compare the planned walls, floor and infill before selecting a profile for the batch. The same sheet suggests printing the first few layers with the cooling fan off to prevent warping, then switching to half fan power. It advises against isopropyl alcohol for cleaning the bed before PETG, since adhesion may become too strong, and prefers window cleaner or warm soapy water.

On cost, total weight depends mostly on unit count and height. Our print cost calculator estimates filament and electricity for a batch from the time and weight your slicer reports. If you are starting from nothing, the startup budget tool helps frame the printer, filament and hardware purchase without relying on random listed prices.

Sources and limits

• GitHub - gridfinity-unofficial/specification · GitHub
• GitHub - Stu142/Gridfinity-Documentation: Documentation relating to the Gridfinity project by Zack Freedman to provide designers with the information to make cool things · GitHub
• Prusament PETG | Prusament

We organize manufacturer and community documentation; we have not measured these products ourselves. The manual for your exact model takes precedence over general guidance.