Just wanted to tell my experience, for those coming here on a tourist visa like me (or already here on one)
I am currently on a 60 day tourist visa, and i just left Jomtien immigration where i extended for another 30 days.
Was given a form to fill out, and was asked for a copy of my passport, a copy of my TM30, and a photo.
They have a copy machine, that will make copies for 10bht. I filled out the form, turn in my paperwork, my number was called and i was basically in and out in 30 minutes. They were pretty firm with the TM30, some people were turn away because they didn't have it, not sure if that's the norm, but make sure you get that when you arrive.
Fairly easy process.
TLDR : Answer Summary
The user shares their experience of extending a 60-day tourist visa in Thailand for an additional 30 days at Jomtien immigration. The process involved filling out a form and providing a copy of their passport, TM30 form, and a photo. It took about 30 minutes, but they noted the importance of having the TM30, as some were turned away without it. Comments from other users include clarifications about the TM30 and experiences with different visa types.