Broos graciously provided exact dimensions for me. I set them herewith for any of you who would like to try this at home. It is really a simple project, and although my entertainment center is a colossus yours need not be!

The Glass Block and Boards Shelf Recipe
1 - 4x8 thing of medium density fiberboard (the sheets I saw varied from $10/sheet to $20/sheet depending on the grain of the fibers; the less expensive, the larger the fiber bits) cut into four pieces of 2x4 each. You end up with, not surprisingly, four shelves.
7 half-sized glass blocks for feet
21 total 8x8 glass blocks (the kind they use to make shower stalls) -- 7 per shelf. We quote the Master Builder: "One at each corner, one in the middle of the front and one in the middle of the back, and then one smack in the middle of the piece of wood, to keep the center from dipping down." You end up with this:

|... --...| <--- the correct placement of the glass blocks.
......|..... (for us visual learners ;>)
|... --...|

Primer (I have a gallon, but I have lots of wood - you might end up only using 1 quart for something this size, depending on how good the coverage is and how many coats you need to seal the wood and keep it from sucking up the paint)
Flat black paint (as much as the primer)
A roller paint brush and pan (or a neighbor with one of them spray painter things; I wish I had one of them).
A large well-ventilated room in which these items can be set up without being stepped on by cats or roommates; my things are in the garage.

Kerplunk the feet, put a board on them, kerplunk a layer of 8x8 blocks and another layer of wood. Repeat. A noted historian recommends wiring the stuff on a given layer before kerplunking the next one. Wise words which our spouse will need to remember, for the variety of his equipment leaves me unable to figure out how to put them together myself.

That said, 2x4 shelves would be really simple and easy to do. Because I mis-remembered the placement of the front blocks, mine is now 3x6, necessitating a lot of huffing and puffing to flip these things over. But I get bonus side shelving too, just need more glass blocks to prop them up with.

This will add the requisite black elements to our living room, which poor Rob prefers. For you know, we are totally opposites. My living room is awash in pale sage greens and golds which gives Rob the creeps; it's too sunshiney. His living room in VA was a tomb, with the windows covered completely by dark bookshelves (not that there's anything wrong with bookshelves). The amount of light in my living room is one of my chief joys and leads him to deep sighs and mentioning how I have tall bookcases that we might want to move...in front of the windows.