Is it better for Jia to make this board flat or round?

Fu Jia flattened the work well. According to the relevant public information, the flat design conforms to the sense of human hands, and the grip is comfortable and stable. The flat design makes the handle fit the palm of your hand better and the operation is natural. The center of gravity of the circle is balanced, and the burden on the wrist is greater when it is used, so Fu Jia's flat handle is more comfortable than the circle. Fu Jia handle refers to turtle shell modeling ornaments. In literary circles, rich armour and rich armour in the world refer to ornaments with tortoise shells as their main shapes.