For your information, applying for a visa by mail is no more accepted. Travellers with the age of majority are requested to apply in person at the Royal Thaï Consulate, Geneva.

Types of visas Purpose of the visit
Diplomatic visas or official visas To enter Thailand on diplomatic or official functions
Transit visas To transit to the country of destination
Tourist visas To travel for tourism (pleasure) purposes only
Non immigrant Visas To study
To visit family
To conduct business
To stay in the Kingdom after retirement
To serve as a volunteer

Download the visa application form (PDF format).
If you need it, you can find the Adobe Acrobat Reader here.