J habite en
Suisse depuis 12 ans, de nationalité Française : je souhaite faire une demande de visa B2 mais j aimerai la faire en
Suisse. Est ce possible ou dois je obligatoirement la faire a
Paris ?
Alors, déjà, au bout de 12 ans, vous avez peut être entamé les démarches pour la naturalisation ?

(ça n'a rien à voir, je sais....)
La réponse à votre question est sur le site de l'ambassade :
"Q.5 If I am a third-country national living in
Switzerland, can I apply for a nonimmigrant visa in
Switzerland?
Applicants are generally advised to apply in their country of nationality or residence. Any person who is legally present in
Switzerland may apply for a visa in
Switzerland. However, applicants should decide where to apply based on more than just convenience or delay in getting an appointment in their home district. One thing to consider, for example, is in which consular district the applicant can demonstrate the strongest ties.
There is no guarantee that a visa will be issued, nor is there a guarantee of processing time. If refused, there is no refund of the application fee."
www.ustraveldocs.com/...en-faq.asp#qlistgen5