Hello Alessio,
ChimeraX does not have a ribbon style editor tool.  You can change the ribbon (cartoon) width, height, etc. with the "cartoon style" command, see:

<https://rbvi.ucsf.edu/chimerax/docs/user/commands/cartoon.html#style>

There are also a few different ribbon presets in the Presets menu.

<https://rbvi.ucsf.edu/chimerax/docs/user/menu.html#presets>

I hope this helps,
Elaine
-----
Elaine C. Meng, Ph.D.                       
UCSF Chimera(X) team
Resource for Biocomputing, Visualization, and Informatics
Department of Pharmaceutical Chemistry
University of California, San Francisco

> On Jul 22, 2024, at 6:38 AM, Alessio Nocentini via ChimeraX-users <chimerax-users@cgl.ucsf.edu> wrote:
>
> Hello,
>
> I have been an academic user of chimera for years. I have just downloaded chimerax but I cannot find the ribbon style editor.
> Can you please help?
>
> Best regards
>
> Alessio