AACG: A Circle in a Rectangle ATC

I saw an idea (on Pinterest, my "shop" of choice)...a little work of art that is, essentially, a circle in a rectangle. The ATC itself is a rectangle...let's create something beautiful that involves a circle that takes up most of the space. You might punch a circle out of a contrasting paper and decorate the circle (sort of like an ATCoin on the ATC); you might draw a circle and use the rectangular ATC as a frame for whatever might be inside your circle; you might even punch several small circles and decorate them in a way that complements your ATC background...use your creativity and make something special for your swap partner!