The 3D light effect of this block is simple to create with the use of a light strip of fabric and a dark strip of fabric
A simple illusion
You can achieve the visual illusion of looking through a window simply by the use of a light and a dark fabric and using a 45 degree angle where they meet (similar to a mitred corner). Valerie shows you how you can achieve this with the simple help of the iron to press in the crease. So no need to panic.
If you would like to check out the mitred corners click here
Vicky Munday has made this lovely example of an Attic Windows quilt She used a pre-printed panel to which she also added the two colours and then she has enhanced the windows effect with the simple quilting.
You could do something similar with a cushion panel too.