3MF Fixer

What this fixes

The file will not open at all

The usual symptom is an error naming a setting and a range, most often:

tree_support_wall_count: -1 not in range [0,2]

Bambu Studio writes -1 to mean “inherit from the profile”. OrcaSlicer and PrusaSlicer validate the number instead, find it out of range, and stop. The same happens with raft_first_layer_expansion. Both are set to 0, which is what the value meant anyway.

Your filament slots get replaced

MakerWorld files name Bambu-only filament presets such as Bambu PLA Basic @BBL X1C, and carry Bambu SKU codes like GFA00 used for AMS auto-matching. A slicer that has none of these substitutes its own defaults, which is what overwrites the filaments you had configured. They are replaced with vendor-neutral equivalents like Generic PLA, including the preset copies embedded inside the project — a half-converted preset makes slicers fall back to an unrelated material such as ASA.

The model prints in the wrong colours, or one colour

Painting is stored per triangle as a filament slot number, not a colour. Two things go wrong. The colours the designer saved are often placeholders, so the parts come out wrong even in a working slicer. And the slot numbering is theirs, not yours — your blue may be in slot 3 while the model asks for slot 2.

Setting colours alone does not survive an AMS re-sync, because slicers map filament N to slot N by position. So the project is rewritten to declare one filament per slot your printer has, in your order, and the paint data is renumbered onto the slots you choose. After that a re-sync changes nothing.

It switches your printer to a Bambu machine

A project file names the printer it was made on. You can pick your own printer after opening, or enter your slicer's exact preset name and the file will be retargeted to it. Each plate is also measured against your bed, so a model laid out for a larger machine is flagged before you slice rather than after.

How to use it

1. Set up your printer once. Bed size, and the colour and material in each AMS slot. It is remembered on your device.
2. Drop in the .3mf. You will see the model rendered from its own paint data, with each painted part listed.
3. Point each part at a slot and download. Open the result in your slicer, sync the AMS, and slice.

Questions

Is my model uploaded?

No. The archive is opened, repaired and re-packed inside this tab using the browser's own compression. There is no server to receive it, and the contents of your model are never sent anywhere. Your original file is never modified — you download a new copy.

So what does the page send?

One thing: Google Analytics, which sets a cookie and records that you visited. There are no ads and no other third-party scripts, and the page is not permitted to contact anything else. Analytics cannot see your model — the file is held in memory and its contents are never placed on the page for a script to read. Filenames are the exception — they are printed on screen as each file is processed, so treat a filename as something it could read. If a filename itself is sensitive, rename the file before dropping it in.

Does it change the model itself?

Never. Geometry is untouched: strip the paint attributes from the input and the output and the mesh files are byte-identical. Only slot numbers and settings change.

Which slicers does it target?

OrcaSlicer, PrusaSlicer, Cura and Elegoo Slicer. Several of these — Elegoo Slicer among them — are OrcaSlicer forks, so they share configuration keys and behave alike.

Does it work on Mac and Linux?

Yes. It runs in the browser, so it works anywhere Chrome, Safari, Firefox or Edge does, including iPad. Nothing to install.

What about single-colour models?

They are repaired too — the preset and printer fixes still apply. There is just nothing to assign.

Missing something?

If the tool should do something it doesn't, or a file came out wrong, say so — send a feature request. It goes straight to the people who build it, and it is the main thing that decides what gets added next. Nothing but what you type is sent; your files stay on your machine.