Hmmm, the shadowbox shown is really attic wwindow with very narrow separators (sills). A true shadowbox should show all four sides of slightly different color value intensity with all four corners mitered. This shows the shadowbox effect of light behind you (usually off to one side) looking at an image in the bottom of a shadowbox. Every square in the quilt has the same pieces in the same position excepting perhaps the bottom blocks, which of course might be different.
Now there is a publication out called Quick Quilts (on sale till April of '07) that has a quilt (Hip to be Square) using so called shadowbox blocks. To me it looks like a big center square with a wide border on it, not even mitered. Not shadowbox in my mind.
The original poster (Charlie) needs to define if the blocks she is thinking of are 3 piece blocks or five piece blocks. In either case, it should be fairly easy to design the composition of the squares and probably paper piece them together. From the description, it sounds like she is looking for Attic Window, easily found in many quilting books as well as on-line. Just Google Attic Window Quilt and see if anything in those 308,000 references looks like what you want.
tim in san jose