if you going to do a few trips travel light and load Ur suit case up you will get 25 kg a suitcase free and they are rarely checked Thailand end , but that's from my own personal experience.
I shipped 8 boxes of personal effects total 130 kg to Thailand last July mostly photos and nick knacks belongings of my parents which is irreplaceable, got raped by customs , so be prepared to pay when it arrives they don't give a rat's.
So if your living in tourist town Hoi An wtf you in this group for we don't care about your life in Vietnam and you had nothing to offer the OP but brag how easy it was in Nam pfft.
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