This may sound like an improbable source, but another idea would be for you to go to some local dollar stores and look around. Back when I was making myself a dice tower, I discovered that some dollar store chains sell (among all the miscellaneous stuff they have in stock) some plain unpainted rectangular wooden trays of various sizes, made of very thin wood. Their designs could not be simpler – a bottom and four sides glued together, all made of flat wooden pieces – and they’re cheap in both price and appearance, but they’re about the right size for what you have in mind and they would probably look quite nice if you applied some dark wood stain to them. And because they’re so inexpensive, picking up as many as you need for your table would be very affordable. It would also be easy to customize them by, for example, subdividing the larger models into sections by cutting some balsa wood sticks (or other types of woods) to suitable sizes and gluing them inside the trays before you stain them.