What do I need to prepare for a single re-entry at the airport in Thailand?

When applying for a single re-entry permit at the airport in Thailand, it's generally recommended to bring your passport and a passport-sized photo. While some users mentioned the option of filling out the re-entry permit form in advance to save costs, others highlighted that at Suvarnabhumi Airport, you don’t need to bring anything extra, as the photo can be taken there.