Do you remember those Stereogram books from a few years ago? This is the cushion version.
Look ‘through’ and you will see that some of the lines of squares appear to be further away than others. Due to careful spacing, the eye perceives some squares to be the background and some the foreground. (The effect is much more obvious on the real cushion than it is in the photo.)
Buy using the link at the top of this page
or in 12 Pillows of Wisdom - a PDF book of 12 cushion patterns