What documents do I need for a re-entry stamp at BKK airport, and where do I go?

Just bring a small photo and you can fill in the document yourself at the counter. And have the 1,000 THB for the single or 3,800 for the double with you in cash.

You will go to this gate.

You go to departure gate 2 after check-in. Go through the security screening, and go down one floor, before the passport control you would see the counter.

You can prepare all necessary documents in hand, or bring only your passport and they prepare everything you need with 200 thb additional service fee.