I used Rico Designs Creative Cotton Aran in 7 colours, Tangerine, Royal, Rouge, Cardinal, Banana, Pink and Bright Green, using a 5mm hook.
I basically followed Attic24's Neat Ripple Pattern, and made 2 squares of rippled goodness the same size, just a bit smaller than the cushion itself.
I then wanted to 'level' the edges of the ripple up, to make it more square for when I joined the 2 sides together. I kept trying different height stitches until I found a pattern than made it roughly straight along the ripply edge. I think from the beginning (which was the top of the ripple) I single crocheted 4 stitches, then half-double crocheted in the next 2, then double crocheted in the next 2 and then single crocheted in the next 8.... and repeated until the end of the row. It wasn't exactly perfect, but a lot straighter. Then I single crocheted down the side of the ripples, which I made up a bit as there were no stitches as such, just the sides of them. But I single crocheted 3 times into each colour stripe, in roughly the same place each time. Then I continued round to level up the other rippled side, and then back along the other side edge, joining with a slipstitch. I also crocheted 2 stitches into the corners to allow for it getting bigger.
I then finished it off with a round of single crochet in green. I'm happy with the result, I love Lucy of Attic24's way of making cushions with old jumpers, but I'm not too hot with the needlework side of things, or sewing machines, so decided to make a double-sided version and work out a way of joining! All that matters is my little P loves it!
Here's the finished article: (excuse the weeds!)
And here it is nestled amongst a lovely fern!
and a close up of the ripples...
one ripplelific little cushion!