Heads up. Border run Chong Sangam today. Non Imm O multi. Cambodian visa 1200bt, leaving fee 300bt. No 'proofs' asked for on re-entering Thailand. Smiles all round from Immigration on both sides. Took about 25 mins out an in.
TLDR : Answer Summary
The user shared their experience of doing a border run from Chong Sangam to Cambodia for a Non-Immigrant O multi-entry visa. They mentioned the cost of the Cambodian visa being THB 1,200 and a leaving fee of THB 300. The immigration process was smooth, with no requests for additional documents upon re-entering Thailand, and the entire process took about 25 minutes.