I decided to DIY it with a piece of custom-cut foam and create my own slip cover with zipper (so it can be cleaned as needed.) The foam is from FoamOrder.com, and, as luck would have it, it turns out that they're located in San Francisco, only two blocks from the flagship Soma Discount Fabric store; I was able to pick up my foam--avoiding delivery charges--and find some upholstery fabric in my color scheme all within two blocks!
When I got the foam and solid plum fabric home, I decided the cushion was going to need a little something to keep it from being boring and settled on adding piping in a fun floral print from Peapod Fabrics, my current favorite place. This meant learning some new techniques--making continuous bias tape and then wrapping it around cotton cord. So worth the effort! And now I want to make tons of bias tape and put it on everything--pillows, leaves of house plants, the cat, you name it.
Like all my successful sewing projects, the finished product is imperfect but just right. (Ahem, yes, I meant to have pleats on only two corners. . . . ) I even had enough extra floral fabric for an accent pillow.
One addition to this project, of which I am most proud, was putting a piece of Ikea STOPP anti slip rug underlay beneath the finished cushion. Thatta way when your crazy three year old decides to jump up and down on the cushion or use it as a launching pad onto the carpet, he will not cause himself greater injury than necessary.
Thanks for reading!