The entire bookshelf unit in my living room was made by my husband. It has twelve enclosures total in two columns with six shelves on each side. The top four shelves on each column are fully enclosed with wood. The bottom two shelves have no wood backing. There is an outlet behind the bottom right shelf, which is where everything is plugged in.

To make a place for me to feed the transformers and cords through, he drilled a three inch circle in the back, bottom, rear corner of the middle vertical wood piece between each of the shelf pairs. Then he drilled a three inch circular hole in the back, bottom, rear area of each horizontal shelf on the right column.

Another way to describe it is to think of the three shelves being on the left side of the bookcase. The cords all feed to the right and go through the side wall of the shelf. Then they go down to the power strip through the bottom of each shelf on the right hand side.

Since the cords are only so long, the power strip is located on one of the middle shelves. Even though the cords feed through the shelves very neatly, and the slack is rubber banded, all those cords and transformers make quite an unsightly mess. The shelf with the power strip has hard back books all to the right. I took one of the hardbacks and placed it facing forward in front of the power strip. While it may look like I'm highlighting a book on the Middle Ages, I'm really using that book to disguise the electrical mess on that shelf.