The wife told me my next project better be a solution to my ever-growing pile of books. I really liked the wedged/tusk idea for the shelves I saw in an American Woodworking magazine plan. My finished bookcase was much different from the one in the magazine due to material constraints. I used what I had on hand: 4/4 ash (sides), 7/8 poplar (shelves), and walnut for the wedges. The poplar was given to me from a farmer who had it sitting in his uncovered barn for 30 years. I planed it down and came out pretty cool… not fine furniture, but still kind of gnarly. I finished with with danish oil (natural) and some paste wax.