I had fun coloring this one using every pen and pencil type I owned. Micros, gel pens, prismacolor pencils, even Staedtler pen for the tiny yellow dots on the outside edge. I don't have every color in any type of pen, so I poked through all of them to get the colors I wanted.
I actually stayed within the lines all the way through and only added a tiny extra on the edge. For me this is unusual. But the shape was a good one right from the get-go.