Here is a parametric model allowing you to make any width extension you want from 10mm upwards. 

The default value is a total spool width of 77mm, this is the narrowest extension possible in this design. Attempting to set it lower than this will still result in a 10mm extension being generated. No fixed limit has been set, so you can make an extension as tall as you can print.

How to use it? 

First, click either “Download 3MF” or “Open in Bambu Studio” at the top of this page. This will use the 3mf profile I have created for this model. It will open with a 10mm spacer already in place. Delete this if you do not need it.

On Makerworld, click on the green “Customize” button at the top of this page.

In the window that opens, type the total spool width that you want in the box, and hit enter on your keyboard or hit the blue "Generate" button. It'll take a moment for Bambus servers to generate the model.

Once the screen has updated to show the model, click the blue “Download button”, select your printer model (if using a non Bambu printer, ignore this dropdown menu), and then hit the blue "Confirm" button. 

You can then download either an STL or a 3MF. I suggest using the STL option and then opening that STL in the 3mf you downloaded at the start of this process. If you pick the 3mf option, it sadly does not use the 3mf profile I have prepared.

No support is needed for printing.

The geometry used is based directly from a Bambulab spool, not that seen on most other printable spools. 

This model was created by me, from scratch, and not by an AI.