We used mason jar lids to stamp black circles on a canvas. V calls them bubbles. My idea was to also add a single red circle, but the girls vetoed and I was out-voted.
It fits in with our very sparse decorating palette and the only cost was the canvas. Mr. Dork asked if I picked it up at a thrift store or someone's back alley. (Once I told him it was made by the girls, he was singing its praises.)