Label your filament - print spool tags straight from the browser
Printed swatches are the honest way to choose a colour. You print the same little chip in every filament you own, drop them in a drawer, and next time you need "that warm grey" you hold three chips against the model instead of squinting at shop photos.
Then the drawer fills up and you hit the problem every swatch collection has: you cannot tell PLA from PETG by looking at it. Same colour, same finish, completely different printing temperature.
So we built a tool for it: Filament labels.
What it does
Pick spools from your catalogue (or just type a material and colour in), choose your label size, and print. Straight from the browser, over Bluetooth, with no vendor app installed.
Three things that matter:
- Material in a black block. Not decoration. White-on-black reads across a drawer in a way ordinary text does not, so PLA and PETG separate at a glance.
- A QR code per spool. Scan a chip with your phone and its page opens: brand, exact colour, and whether the spool is free or lent out right now.
- Nothing to install. No app, and no account for manual entry.
Why the QR? This is the part a generic label maker cannot do - it does not know your shelf. It turns the label from "a piece of plastic, PETG" into a live link back into the catalogue.
What you need
A NIIMBOT label printer and a browser that speaks Web Bluetooth:
| Device | Works? |
|---|---|
| Chrome / Edge on desktop | Yes |
| Chrome on Android | Yes |
| iPhone, iPad | No |
| Firefox | No |
iOS is a dead end. Safari has no Web Bluetooth and Apple does not let other browsers add it, so there is nothing to work around. The tool offers a PNG download instead, which you can print from the official app. In Brave you may need to turn Shields off, or the label picks up speckles.
Choosing a printer
NIIMBOT sells a confusing number of models. For labelling filament, only two numbers decide anything.
1. Printable width
The print head is a fixed strip of dots, and that is the hard ceiling on label width. This is the number that rules models out: a 12 mm head simply cannot print a scannable QR next to text.
2. Resolution
Almost every NIIMBOT is 203 dpi, which is 8 dots per millimetre. The B21 Pro is 300.
It matters less than you would think for text - 203 dpi prints a readable colour name at 3 mm. It matters a lot for QR codes, because a QR is only reliable when each module lands on enough whole dots.
The models side by side
| Model | Resolution | Printable width | Good for |
|---|---|---|---|
| D11, D110, B18, H1S | 203 dpi | 12 mm | Swatch chips, narrow strips |
| D101 | 203 dpi | 24 mm | Swatch chips with more text |
| B1, B21 | 203 dpi | 48 mm | Spool labels, text plus QR |
| B21 Pro | 300 dpi | 50 mm | Spool labels with the crispest QR |
| B3S | 203 dpi | 72 mm | Wide labels, bins and shelves |
Widths are calculated from the print-head data the tool itself uses, not from marketing copy.
So what should you buy
Only tagging printed swatches? A D11 or D110 is plenty and it is the cheapest way in. Twelve millimetres fits a material tag and a short colour name.
Want QR codes on the labels? Go wider - a B1 or B21. On a 12 mm strip a QR ends up with modules well under a third of a millimetre, and phones start failing to read it.
Buying new and want the best of it? The B21 Pro. Same 50 mm width, but 300 dpi, which is the nicest of the lot for QR codes.
Before you order cheap rolls: many NIIMBOT rolls carry an RFID tag that the printer verifies, so third-party labels may be refused. Look up your specific model before betting on generic consumables.
Two practical notes
Thermal printing is monochrome. You cannot print the filament's colour - a colour swatch comes out as a black rectangle. Let the name carry the colour, and let the physical chip show it. That is why the material tag is the loudest thing on the label.
Bigger labels make better QR codes. If a QR has to be there, height is what buys you scannable modules. A 40 x 30 mm label gives you comfortably readable codes; on a 40 x 12 mm strip, consider dropping the QR and keeping the text.
The tool measures the module size for you and warns when it drops below the readable threshold - before you print a whole roll of labels nothing can scan.
The tool is free and needs no account for manual entry. Sign in and it pulls straight from your catalogue - including the QR that leads back to it.