This alternative version of the Attic Window Quilt Block is a great study in 3-D illusions. With the right selection of colors, this block gives the effect of an inset window. The block could be made with y-seams, but an easier version (shown below in the Block Construction section of this page) is to divide the block into an uneven four-patch. The y-seams are eliminated and replaced with a simple half square triangle.
Shown below are a few groupings of Attic Window Quilt Blocks set in straight sets. The first one is set with sashing strips; the second without.