I am planning on building a 4x10 expansion back for my old 5x7 linhof technica and I am looking for some advice on wood. I have an ebony and that is really nice but probably too expensive. It seems that walnut has been pretty popular. I guess hardness and resistance to expansion and contraction because of moisture are the most important factors here. i was thinking of using oak because i have some. Any advice or experience will be of great help here.