Inlaying two wooden pieces into a metal frame
I have a metal frame that takes the shape of a yin and Yang. It is 1/2″ thick stainless steel that is 18″ in diameter so the pieces of wood I am laying in are roughly 9″x 16″. I want to use two natural toned woods. One very dark one very light. I then want to cut a hole in each piece toward the center and in lay the other piece of wood, to complete the yinyang design.
My two question are, how should I fit the wood into the metal frame to ensure that wood does not crack over time if it expands at all (piece will be indoors)? and What two types of wood should I look for that have good light/dark contrast?
I am from Wisconsin for reference and have access to a large lumber yard with a lot of options.