You caught the Gridfinity bug, printed a baseplate and a wall of neat little bins, and it felt great for about a week. Then you tried to store the one thing you actually wanted to store: a specific caliper, a roll of a specific tape, a handful of a specific connector. None of the pre-made bins on Printables are the right size for it. They are close, and close is exactly the problem. The pen rattles in the 1x1, or the tool is 3mm too long for the 2x1 and you are back to a pile on the bench.
The fix is a bin sized to your thing, not to an average of everyone's things. The catch is that the usual routes to a custom bin want you to edit OpenSCAD variables or fight a browser generator that hands you a frozen STL you cannot nudge afterward. This guide covers the Gridfinity numbers that actually matter, how to size a bin to a real object, and how to get a custom, editable bin without opening CAD at all.
What is Gridfinity, in plain terms?
Gridfinity is an open, community-maintained standard for modular storage: a grid of baseplates, and bins that drop into that grid and can be rearranged like Lego. It was created by Zack Freedman and released for anyone to build on, which is why there are thousands of compatible bins, tools, and generators floating around the maker web.
The whole idea is interoperability. Any bin that follows the spec fits any baseplate that follows the spec, from any designer. So you do not have to commit to one person's bin library. You can print a standard baseplate, then fill it with a mix of stock bins and your own custom ones, and everything still lines up and locks together.
What are the key Gridfinity dimensions?
The spec comes down to two numbers: every grid cell is 42mm by 42mm, and every height step is 7mm. Bins are sized in whole grid units (1x1, 2x1, 3x2, and so on) and whole height units. Get those two right and your bin is compatible; everything else is detail.
Here are the numbers worth knowing before you design one:
| Feature | Value | Why it matters | |---|---|---| | Grid cell | 42mm x 42mm | One "unit" of footprint; bins are multiples of this | | Bin base footprint | 41.5mm per unit | Slightly under 42mm so a bin drops into the baseplate | | Drop-in clearance | ~0.25mm per side | The gap that lets a bin seat without forcing it | | Height step | 7mm per unit | Bin height is a multiple of 7mm | | Magnet hole (optional) | 6mm diameter x 2mm deep | For 6x2mm disc magnets in the base corners | | Screw hole (optional) | M3, in the corners | Screw a bin down or add weight if you skip magnets |
That 41.5mm base is the quiet hero. The bin is a hair smaller than the 42mm cell so it slides into the baseplate's socket and sits held by a small lip, snug but liftable. It is the exact same clearance thinking you use for any printed part that has to mate with something: the modeled size and the fitting size are not the same number, and the standard already bakes in the gap for you.
How tall should a Gridfinity bin be?
Pick the shortest height, in whole 7mm units, that still clears whatever goes inside. A bin of 3 units gives you roughly 21mm of usable depth, and 6 units gives you around 42mm. Taller bins waste plastic and print time; shorter bins let short items poke up where you can grab them.
Match the height to the contents, not to a default. Loose screws and SMD components want a shallow 2 or 3 unit bin so you can scoop them out with a finger. A stack of hex keys or a roll of tape wants a taller 5 or 6 unit bin so it does not tip. If you are storing something long and skinny standing up, like drill bits, measure how far it sticks up and round the bin height to the next 7mm step above that.
| What you are storing | Start here | Why | |---|---|---| | Loose screws, resistors, SMD parts | 2 to 3 units (~14 to 21mm) | Shallow enough to scoop out | | Hand tools laid flat, connectors | 3 to 4 units (~21 to 28mm) | Holds them without burying them | | Rolls of tape, taller bottles | 5 to 6 units (~35 to 42mm) | Keeps tall items upright | | Bits or pens standing up | Next 7mm step above the item | So it clears but does not swim |
How do I size a custom bin to fit a specific tool?
Measure the object, add 1 to 2mm of wiggle on each side, then round the footprint up to whole grid units. The grid is your constraint, so you are choosing the smallest number of whole cells that contains your object plus a little breathing room.
Work it in three steps:
- Measure the thing. Length, width, and how tall it stands. A pair of calipers beats a tape measure here, because being 2mm off is the difference between "drops in" and "wedges."
- Add clearance. Give it 1 to 2mm of gap per side so it drops in and lifts out without a fight. A 60mm wide tool wants roughly 63 to 64mm of interior.
- Round up to the grid. One cell is 42mm of pitch, so a 1x1 bin gives you about 36mm of usable interior after walls, a 2x1 gives about 78mm along the long axis. Your 64mm tool needs a 2x1. A 90mm tool needs a 3x1. When in doubt, go one cell bigger and add a divider.
The reason this is worth doing at all, instead of grabbing the closest stock bin, is that a bin built for your object holds it still. A caliper in a bin cut to its outline does not slide around every time you pull the drawer. That is the whole promise of printing your own, and it only takes three measurements.
Do I need magnet holes and baseplates?
You need a baseplate for the grid to mean anything, but magnet holes are optional. Bins sit in the baseplate's socket and are held by a lip; magnets or M3 screws in the base corners just add extra hold-down so a bin does not lift out when you do not want it to.
Skip the magnets if your bins live in a drawer or on a flat shelf. Gravity and the socket lip are plenty, and you save the cost and the fiddly job of pressing 6x2mm discs into every corner. Add magnets (or a screw and a steel baseplate) if the grid is wall-mounted, tilted, or gets jostled, where a loose bin would actually fall out. For most desk and drawer setups, plain socketed bins with no magnets are the sensible default.
What is the easiest way to make a custom Gridfinity bin without CAD?
The three common routes are an OpenSCAD parametric library, a web generator, or describing the bin in plain English and getting real editable CAD back. They differ mostly in how easily you can fix a bin after the first print comes out slightly wrong.
| | OpenSCAD library | Web generator | Describe it in Meshra | |---|---|---|---| | How you specify it | Edit code variables | Click through a form | A plain sentence with your sizes | | Learning curve | Some scripting | None | None | | Editable after? | Re-edit, re-render | Usually a frozen STL | A slider for every dimension | | Fix a wrong size | Change a variable, re-render | Regenerate from scratch | Drag a slider, re-export | | Files you get | STL | Mostly STL | STL, 3MF, STEP, GLB |
A frozen STL is the trap. If your first bin is 2mm too tight or one grid unit too short and all you have is a mesh, your only move is to generate the whole thing again and hope. A parametric part keeps every dimension as a number you can change, so a bad fit is a nudge, not a redo.
How do you make a Gridfinity bin you can actually tweak?
The reliable path is to start from a bin that is already grid-accurate and then tune it, so you never risk breaking the 42mm and 7mm math by hand. That is exactly what Meshra's Gridfinity Bin starter is for.
In Meshra's template gallery, open the Gridfinity Bin starter (in the Maker category). You pick the grid width and depth in whole units, the height in the standard 7mm units, and an optional front scoop cutout for scooping small parts out easily. It builds instantly with no AI generation used, because a starter is deterministic code, not a fresh AI build, and it lands in the builder with a slider for every one of those dimensions. Set it to 2x1, four units tall, and if the tool is still a touch snug, drag the size up a millimeter and the bin regenerates on the spot. That re-run is free on every plan, because it is the same program run again with one number changed.
Want a bin the starter does not cover, like a specific divider layout? Describe it in plain English instead, for example "a 3x1 Gridfinity bin, five units tall, split into three equal compartments." Meshra writes real parametric CAD from that sentence (CadQuery on the OpenCascade kernel, the same exact-geometry engine pro CAD tools use) and again gives you a slider for every dimension you named. Either way, when the fit is right, export STL or 3MF straight to your slicer, or STEP if you want to keep editing in other CAD. The printability summary even shows a build-volume fit check, so you can confirm a big multi-cell bin fits your bed before you commit filament to it.
Frequently asked questions
What is the Gridfinity grid size? Every grid cell is 42mm by 42mm, and bins step in height by 7mm units. A bin's base footprint is 41.5mm per cell, slightly under 42mm, so it drops into a baseplate with about 0.25mm of clearance per side and sits held by the socket lip.
How do I make a custom-size Gridfinity bin? Measure your object, add 1 to 2mm of clearance per side, then round the footprint up to whole grid units (1x1, 2x1, 3x2, and so on) and pick a height in whole 7mm units that clears it. Start from a parametric bin so you can tune the size with a slider instead of regenerating a frozen mesh.
Do Gridfinity bins need magnets? No. Bins are held by the baseplate's socket lip, so magnets are optional. Add 6x2mm disc magnets (or M3 screws) in the base corners only if the grid is wall-mounted, tilted, or gets knocked around; for a drawer or a flat shelf, plain socketed bins are fine.
What material should I print Gridfinity bins in? PLA is the easy default: stiff, cheap, and a storage bin never gets hot or load-bearing. If the bins live somewhere warm like a garage or hold something with a bite (solvents, sharp metal), step up to PETG. See PLA vs PETG vs ABS for the full comparison.
How thick should Gridfinity bin walls be? The standard bin wall is thin on purpose to save plastic, and it prints fine because there is no structural load. Two perimeters (about 0.8mm at a 0.4mm nozzle) is plenty for a light storage bin; see how thick walls should be if you are adapting a bin to hold something heavy.
Where to start
Pick the one thing that never has a home on your bench, and measure it: length, width, and standing height. Add a millimeter or two of clearance per side, round the footprint up to whole 42mm grid cells, and round the height up to whole 7mm units.
Then open the Gridfinity Bin starter in the template gallery, set those grid and height numbers, and add a front scoop if you want one. It builds free with no AI generation, and every dimension is a slider, so dialing in the last millimeter of fit is a drag, not a reprint. Prefer to describe it in words instead? Head to the builder. See pricing for the plans and limits.
Gridfinity's genius is that the grid never changes, so your bins always fit together. Your job is just the inside of the bin, and that is one object, three measurements, and a couple of sliders away.
