Measure the area you’ve identified as optimal for constructing your tall room divider. Mark up an outline on the floor with chalk if you have wood floors or use colored tape if it's carpeted. Assess the amount of pass-through space you’ve allocated on one or two sides to make certain the structure won't hog too much space. Check for electrical outlets and wall switches.
Purchase enough unfinished bookcases -- 96 inches high, 36 inches wide and 12 inches deep -- to run the length of the area reserved for the room divider. Double the number of units if your space can comfortably accommodate a little over 24 inches of depth to provide shelving on both sides of the divider. Drill discreet holes in the backs of the bookcases if you intend to install lights above shelves.
Sand and stain or paint the bookcases to match your décor. Seal the units with polyurethane, particularly if items you intend to display on the shelves have the capacity to discolor or mar surfaces. Add a dramatic touch by painting the back walls of interior shelves with an accent color to add interest, and repeat one dominant room color. Hang a large piece of art or a small, framed collection of photos on the backside of the unit if you’ve installed just one row of bookcases.
Feed wiring for the lighting network into each unit before you line up the first row of bookcases. Check the lineup of bookcases for uniformity before backing the second row of bookcases against the first row. Interface and connect the lighting system to the pre-installed wiring. Plug it in and test it to make sure everything works.
Decorate the shelves with memorabilia, music, books, art and photos. Reinforce themes on both sides of the tall room divider to reflect the colors and styles of furnishings and decorative touches. Display household items such as crystal glasses, platters and candles on shelves facing the dining room, for example, with your classic book collection on shelves facing the living room.
Add silk greenery, baskets or items too tall to be displayed on shelves to the top of your tall room divider to add height and soften the look. Use the top of your room divider as a staging area for Christmas cottages, Halloween decorations and other holiday décor that rotates often enough to make sure your tall room divider gets dusted now and again.