Still, last weekend I pulled a late night (aka hey, look it's finally less than 30deg C in my appartment) ironing session to shape the clam shells, and the rest of the sewing is blessedly ironing free (or nearly so), so putting the pillow together was an option.
The pillow is 50 x 50 cm (20 inches). I did some spiral quilting (which was super fun to do. I see more of that in my future)
Not sure if I want to do the clam shell technique again (don't see a whole quilt of that, that's sure), but at least I did it once, so for now it's out of the system.