All you need is: An old, used particle-board bookcase, a pneumatic nail-gun, some wood glue, and access to a home-supply-store.
Step 1: Remove All Shelves.
These bookcases usually have several removable shelves with one held in place by screws, I assume for support. Take out any and all shelves except that one. The image shows what I had left.
Step 2: Make Boxes!
It should be iterated that I nailed these boxes from the side so that the weight pulling downwards won't pull the nails out. This means that I had to measure the depth of the boards and add that to the sides.
Also, at about this step I figured out how many new shelves I was going to have to buy. For this I used 4 extra shelves, then cut them for supports as shown in the final step.
(TIP: I had a Speed Square (y'know, basically a metal right-triangle) on hand to square up the sides of the boxes.)
Step 3: Measure, Measure, Measure!
After lining everything up just right, again, using the speed square, I used my roomate's pneumatic nail gun and secured all of the shelves, both to the boxes and to the sides.
When constructing this, I found it was easiest to measure the top and right side of each box, cut the appropriate length pieces, nail them in place, and then--only then--did I measure the other two supports for the bottom and left sides of the boxes.