It is not so relevant, but how are you going to create x1g, or x6g? You would need two 8g right?
For accuracy, you may achieve what you want, but it doesn't seem easy to use, especially when you have to add and subtract weights to find out critical weight at which a switch actuates.
Also, instead of looking for 8g, 9g Hungarian coins, I think it would be better to buy a cheap jeweler's scale and make custom weights from whatever material. They only cost 5 bucks on ebay.