Once in a documentary I saw an exquisite Go Set.
The stones were not double or single convex, they were actually balls (round spherical stones).
The board had carved channels or grooves, so as you put a ball to an intersection it stayed there.
I tried to find such a board on the internet and could not even find a picture.
Does anybody know of such boards?
(I am not interested kurokigoishi boards, they might be exquisite, but they are not balls).