Regular readers of this blog, and people who have seen me speak, already know that I like to use as much reference as possible for my illustrations, from photographs to...models:
Turns out it's really difficult to find good pictures of blue whales. I guess they're to big to photograph. There are a lot of good illustrations of them out there, and those were helpful, but what really helped me on this book was a nine-inch-long plastic blue whale toy. I think you'll understand why when you see more illustrations from the book.
And, as I often do, I sculpted a little model of the titular character, Billy. He's made out of Sculpey and painted with acrylics.