You can if you can get there. The issue is there is quite a substantial distance between the Thai border post and the Myanmar one, several km along a dirt road. You could possibly do it if you had your own transport, don't know if you can take a motorbike in though. If you make your own way to the border at Ban Phu Nam Ron (there is a regular public bus from Kanchanaburi), there is a "taxi service" there that will take you over to Myanmar, IIRC around 800-900B including the cost of the Myanmar stamp (theoretically $
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B on its own). It may be difficult to get back as well, I ended up hitchhiking. The border really is in the middle of nowhere.