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Wapi scales are maybe 5/64 if memory serves... not sure though never owned one. I'm sure someone else could get you a firmer number. If it were me, I'd shoot for around 1/16 in a metal scale.

You might have to work a bit to get the balance right, as others have pointed out, but they look really cool. Definitely going to be a nice set of scales when you're done with them!