I used this pattern with a 3.25mm hook and doubled embroidery floss.
I made the pillow from a couple of dinner napkins and did a blanket stitch around the edge. it was a little time consuming but I'm happy how it came out :)
I liked using the embroidery floss for this because I could get so many different colors and I only needed a little for each square so it didn't cost a lot to have a variety of colors. the strands would separate once in a while, so I wasn't able to crochet as fast as I normally would and needed to really pay attention so I didn't pull up a strand from the wrong loop, but other than that it was pretty easy to do.