---
title: "A custom Gridfinity bin sized to what it holds: dividers, label tab, magnets, your drawer"
description: "The Gridfinity numbers (42 mm grid, 7 mm units), how to size a bin from the drawer and the tools, and the prompt that designs a bin with your dividers."
canonical: https://speakcad.com/blog/custom-gridfinity-bin-sized-to-what-it-holds
published: 2026-10-19
updated: 2026-10-19
publisher: SpeakCAD
---

# A custom Gridfinity bin sized to what it holds: dividers, label tab, magnets, your drawer

> The Gridfinity numbers (42 mm grid, 7 mm units), how to size a bin from the drawer and the tools, and the prompt that designs a bin with your dividers.

Gridfinity works because every bin and baseplate shares the same base: a 42 mm grid, feet that drop into the plate's sockets, a lip that lets bins stack. Thousands of bins are published, and the one you need, the bin with three slots sized to your three screwdrivers, is never among them. The fix is to design the bin for the thing, on the standard base, so it still drops into the plate you already printed.

## The numbers that matter

- **Grid: 42 mm.** A bin that is 2 units wide spans two sockets, 84 mm of grid. Bins are made 0.5 mm smaller than their grid span (a 2 × 1 bin is 83.5 × 41.5 mm) so neighbours do not rub.
- **Height: 7 mm units.** A bin's height is counted in units of 7 mm, base included. The usual sizes are 3 units (21 mm) for small parts, 6 units (42 mm) for tools standing up, 9 units (63 mm) for tall things.
- **The base** is a profile of about 5 mm with the chamfered feet that seat in the baseplate; it is the same on every bin and it is the part you must not improvise.
- **The stacking lip** at the top lets another bin sit on this one; skip it when you want a flat rim to grab.
- **Magnets** are 6 × 2 mm, one in each corner of each cell, pressed into a 6.5 mm pocket from below. Only useful for a plate with magnets.

## Choose the footprint from the drawer, the height from the tools

1. **Measure the drawer inside**, width and depth, at the front. Divide each by 42 and round down: a 300 × 200 mm drawer takes a 7 × 4 baseplate (294 × 168 mm), with a few millimetres spare.
2. **Check your print bed.** A 4 × 4 bin is 167.5 mm square and fits a 180 mm bed; 5 × 5 is 209.5 mm, for a 220 mm bed or larger; 6 × 6 is 251.5 mm and needs a 256 mm bed. [What bed size you really need](/blog/what-print-bed-size-do-you-need) has the numbers for the common printers; bigger baseplates print as tiles.
3. **Height from the tallest thing lying in it**, plus 3 mm, rounded up to the next 7 mm unit. Tools standing up want 6 or 9 units.
4. **Dividers from the contents**, not from symmetry. Lay the tools on the desk in the arrangement you want, measure each one's width, add 1 mm each, and that is your slot list.

## What to specify

A bin that fits the first time comes from a prompt with the size in grid units, the height in units, and the dividers in millimetres. The AI in SpeakCAD builds the bin on the standard Gridfinity base profile, so it seats in a standard plate and stacks under a standard bin. Say:

- the footprint ("2 × 3 Gridfinity bin") and the height ("6 units tall")
- the compartments, with sizes ("three slots along the long side, 14, 18 and 24 mm wide, full depth")
- the extras: a label tab on the front, a finger scoop at the back, magnet pockets or none, stacking lip or a flat rim
- what goes in it, so the walls and the scoop make sense ("for Wera screwdrivers with 32 mm handles")

Once it renders, turn it over to check the feet, read the slot widths in the dimensions panel, and change what is off: "make the middle slot 20 mm" is a small change; on a plan, each part's first 3 small changes are included.

## Printing a bin

Bins print upright with no supports: the feet are chamfered for exactly that. 0.2 mm layers, 2 walls, 10 to 15 % infill is plenty, since the walls do all the work. Dividers thinner than 1.2 mm come out flimsy; 1.6 mm is the comfortable minimum. PLA is fine in a drawer; PETG for a garage that gets hot in summer. G-code sliced for your printer downloads next to the STL, with the same credits.

## A baseplate too

If the drawer has no plate yet, ask for one with the same grid ("a 7 × 4 Gridfinity baseplate, split into two tiles that fit a 220 mm bed"). The AI cuts the split on a grid line so the bins straddle the joint without noticing.

If you have never measured for a print, [how to measure an object for a 3D printed part](/blog/how-to-measure-an-object-for-a-3d-printed-part) takes ten minutes and saves a reprint.

Shaping a part by hand (a hole, a cut, an added shape, text, rounded corners, a shell, every size typed in millimetres) is free, and so is downloading what you shaped. With the AI, a new part spends 4 credits on a plan with its first 3 small changes free, a design change 3, a small change 2, a quick edit 1; without a plan a new part spends 3. Start with Maker: 50 credits a month for $7.99, cancel anytime.

## Prompts to try

- A 2 x 3 Gridfinity bin, 6 units tall, three slots along the long side 14, 18 and 24 mm wide for screwdrivers with 32 mm handles, label tab on the front, no magnets ([open in SpeakCAD](https://app.speakcad.com/signup?next=%2F%3Fprompt%3DA%25202%2520x%25203%2520Gridfinity%2520bin%252C%25206%2520units%2520tall%252C%2520three%2520slots%2520along%2520the%2520long%2520side%252014%252C%252018%2520and%252024%2520mm%2520wide%2520for%2520screwdrivers%2520with%252032%2520mm%2520handles%252C%2520label%2520tab%2520on%2520the%2520front%252C%2520no%2520magnets))
- A 1 x 2 Gridfinity bin, 3 units tall, split into 4 equal compartments for M3 screws, finger scoop at the back, stacking lip ([open in SpeakCAD](https://app.speakcad.com/signup?next=%2F%3Fprompt%3DA%25201%2520x%25202%2520Gridfinity%2520bin%252C%25203%2520units%2520tall%252C%2520split%2520into%25204%2520equal%2520compartments%2520for%2520M3%2520screws%252C%2520finger%2520scoop%2520at%2520the%2520back%252C%2520stacking%2520lip))
- A 4 x 3 Gridfinity baseplate with 6.5 mm magnet pockets, in one piece for a 220 mm bed ([open in SpeakCAD](https://app.speakcad.com/signup?next=%2F%3Fprompt%3DA%25204%2520x%25203%2520Gridfinity%2520baseplate%2520with%25206.5%2520mm%2520magnet%2520pockets%252C%2520in%2520one%2520piece%2520for%2520a%2520220%2520mm%2520bed))

## FAQ

### What are the Gridfinity dimensions?

The grid is 42 mm; a bin is 0.5 mm smaller than its grid span, so a 2 x 1 bin measures 83.5 x 41.5 mm. Height counts in 7 mm units, base included: 3 units is 21 mm, 6 units 42 mm. Magnets are 6 x 2 mm in a 6.5 mm pocket at each corner of each cell.

### Can I make a Gridfinity bin with my own dividers?

Yes. Type the footprint in grid units, the height in units and the slots in millimetres into SpeakCAD, with what the bin holds; the AI builds it on the standard Gridfinity base so it seats in any standard baseplate.

### What Gridfinity bin fits my printer?

A 4 x 4 bin is 167.5 mm square and fits a 180 mm bed; 5 x 5 (209.5 mm) needs 220 mm; 6 x 6 (251.5 mm) needs a 256 mm bed. Bigger baseplates print as tiles split on a grid line.

## About SpeakCAD

SpeakCAD is the most intuitive CAD for 3D printing, made for people who own a 3D printer and need a part that fits something they have: tap a face and type a size to shape it with simple tools, or describe it to the AI, on your phone or computer, and download a print-ready STL, 3MF or G-code sliced for your printer.

SpeakCAD works inside ChatGPT and Claude as a plugin (an MCP server): ask the assistant for a part with its measurements and SpeakCAD's own CAD AI designs it, shows it in 3D in the chat and hands over a print-ready STL, 3MF or G-code sliced for your printer.

- Live demo, no account: https://speakcad.com/demo
- In ChatGPT, Claude and other MCP clients: https://speakcad.com/chatgpt-plugin, https://speakcad.com/claude-connector, https://speakcad.com/mcp-server
- Pricing: https://speakcad.com/pricing
- FAQ: https://speakcad.com/faq
- Site index for AI assistants: https://speakcad.com/llms.txt