While the quilt you linked to is reminiscent of Tumbling blocks you have discovered that most Tumbling blocks are assembled using all diamond shape units. Because you want to frame a square 9P with the 3d effect, look into the pattern Attic Windows for your assembly. You can skip the set in seam by using a HST as the corner unit of the sashing (note that the seam is better concealed if you use a print fabric that "reads" solid, rather than a solid). Then set your completed blocks on point and you should get the effect you are looking for.