I built this large red mahogany bookcase for someone I work with, it will be used for DVD storage. They happen to have a large movie collection and asked me to build this at 85" tall, 55" wide, and 10" deep.
I used part of two sheets of 1/2" oak plywood for the back. After building it and attaching all of the deck boards I sanded it and then stained it. After staining I applied one coat of semi-gloss polyurethane.
Next, I lightly sanded it again before applying the second and final coat of polyurethane.
After it was finished I attached the back pieces using 1 1/4" wood screws.