Hi Alvin, we just did it last Thursday, so you need to make photos, photocopies of passport biodata page as well as your visa/stamp page, photocopy of TM6 card (recto/verso) and fill in TM7 formular. We wrote TOURISM as the reason as already said in previous comment. Do not forget the 1900 THB fee in cash. We arrived there quite late like 15h15 knowing there is limit to get to the "queuing" at 15h30. You will need then to go to Counter K on 4th floor. They provide pens, scissors and glue to stick photo on TM7. One agent will check documents quickly, stapling them together ang giving you a "queuing" tag then you go to an other room to process the document and pay your fee, taking a photo of you, you wait to get back your passport et voilà, it is done ;-)