We used 1/2" Oak for our project. I don't think that the type of wood really matters. It's important to cut the slots just a little thicker than the knife you use to cut your bread.
     Measure a fresh load of bread for height, length and width. Ours ended up being 5 1/2" X 5 1/2" X 8". Cut the bottom and end pieces the width of the loaf (5 1/2"). Cut the bottom to the length of the bread (8"). Cut the end and sides to the height plus the thickness of the bottom piece (6").
     Lay out your cut lines for the slicing part. We made six slots 1/2" wide. The first slot from the end is in 1" to account for the thickness of the end piece. We made a nice looking curved line toward the front but you could cut it straight at an angle.
     Put the two sides together and either clamp them, tack them or use double back tape to keep them together while cutting. We used a band saw to cut the slots. We had to move the blade up and down in the slot to widen it a little to match our knife width.
     Glue and nail the pieces together and go slice some bread. We decided not to put any finish on this piece since it's used on food.