Gridfinity, or building someone else's standard
24 August 2026
Most of my generators get to pick their own numbers. A drawer organizer is right when it fits your drawer. A Gridfinity bin is right when it clicks into a baseplate printed by a stranger three years ago from someone else's file. Every dimension is already decided, published, and multiplied across thousands of printers. My job was only to reproduce it exactly and then make the options pleasant.
The grid is 42 mm. Height comes in 7 mm units. The magic is in the foot. From the bottom up it goes 0.8 mm at 45 degrees, 1.8 mm straight, then 2.15 mm at 45 degrees again. That is 4.75 mm in total, under a 41.5 mm square top rounded at 3.75. The stacking lip on top of a bin is the same profile flipped into a negative, which is why a bin sits in a baseplate and also on another bin. Change any of these and your parts stop mating with everyone else's, so in the source they sit in one block with a comment telling me to keep my hands off.
Where it fought back
The bug that ate an evening was invisible in the preview. Feet, body and lip are separate solids, and my first version stacked them exactly on top of each other, face touching face. The boolean library takes such perfectly tangent faces and quietly produces a mesh that is no longer a valid solid. Nothing fails at that moment. The failure comes two steps later, when the magnet pockets refuse to cut and the finished bin prints with blind holes. The fix is embarrassingly small. Every part now overlaps its neighbour by 0.2 mm, so no two faces are ever exactly coplanar. There is a comment in the geometry marking it as a family rule, because the same trap exists in every generator that joins solids.
Pockets are carved into the plain body slab first, while it is still a clean extrusion, and only then the feet and lip join. Doing it in the other order used to trip the cuts on the lip's chamfers.
The options
A bin can be 1 to 8 units on each side, up to 18 units (126 mm) tall, and the span is capped at 350 mm so it still fits a large bed. Compartments divide it into up to 8 by 8 cells, each with a quarter-round scoop at the front so small parts roll onto your finger instead of hiding in a square corner. There is a 12 mm label ledge along the back if you want to write on your storage. Every foot corner has a pocket for a 6.5 by 2.4 mm magnet, press-fit from below with a drop of glue, and an optional M3 through-hole sits concentric with it for people who bolt their plates down.
Walls go from 0.8 to 2.4 mm. The default is 1.2, which survives being tossed into a drawer; 0.8 is for people counting grams.
Baseplates are the boring half and I say that with affection. A flat plate with socket negatives, no supports, mostly air. Print as many as fill the drawer and butt them together; the bins do not care where one plate ends.
One thing I would not have guessed
The 45 degree angles in the standard are not styling. Every chamfer on the foot and the lip is self-supporting, so a bin prints feet-down with zero supports, and the lip's inward overhang rests on a 45 degree shrink of the wall below it. Whoever designed this drew it around an FDM nozzle from the first line. Reproducing it gave me more respect for the original than using it ever did.
Yesterday the Gridfinity generator got 100 requests, five times more than the day before, and the most common bin was a plain 1x1. People apparently start every grid the same way I did, with one small cube to see if it clicks. It does.