Hi Anis,

> How about Rhino, can I create the fillet in Rhino ?
> What kind of geometry library behind Rhino ?

No, you can't really rely on Rhino for that purpose.

Rhino has a custom in-house developed geometry library.

For filleting you'll want to have something that uses the ACIS or Parasolid libraries which are more mature in this area.

- Michael