What is the best format to import a solid out of Rhino into Catia?
It depend what kind of object you need in Catia.
A closed solid polysurface from rhino using step will convert into a solid body in Catia.
If you need closed volume or (VolumeGeo) inside catia, you cannot get it with any format whatsoever.
If you export to IGES in catia you’ll get a surface object (which is not a volume, neither a solid)
There are options in IGES export from Rhino for Catia Solids or Catia Surfaces. You can try those out.
in catia there is a difference between closed volume object (which is surfacic object in GSD application) and solids which are used in the Part Design application. These two objects have different attributes and properties.
That’s why I asked it depends on what kind of object he expects to get after importing in Catia.
(By Catia I assume CATIAv6 (3DEXPERIENCE) I haven’t worked with v5 in more than 5 years.
I would say that the best format is Catpart (If you talk about CATIA V5).
You can get .catpart files from Rhino with a plugin (https://www.datakit.com/cad-convertors/rhino-to-catia-v5-3d/1775-rhino-3d-to-catia-v5.html).