bags of time then!
I cant help with a plan, but the one that zed linked to looks to be quite simple and screwwed together- I would modify it slightly and make a simple mitred box, rebated top and bottom to take the lid (and base), then sliced off at 1/4 and 3/4". I would probably put spline keys in for strength. A nice lining will transform the piece- a nice bit of pigskin would be my choice (since I have some), but anything soft and luxurious would do.
You could rebate in the "shelves" from behind before gluing in the base. Finally, mount the whole thing on a base slightly wider than the closed box. The shelves seem to be notched thin strips.
Size wise, a guess, but i would mock something up in cereal box and tape, guessing around about 200mm tall, 120mm deep and 120mm wide, as you look at the finished article. you can adjust it when you see it.
