This project was also for my neighbor and was designed to mimic his antique stackable barrister bookcases.  The entire piece is made up of 6 modular units that stack on top of each other using interlocking wood slats.  It rests on a dedicated base and is topped-off by a decorative cap.  Each unit features a retractable glass door with custom wood handles.  All assembled, the bookcase is about 5 and a half feet tall and almost 3 feet wide.  Constructed from red oak and oak plywood, the piece was finished in a two-tone fashion with a brown maple-colored interior and a dark walnut/mahogany exterior.