A spraying background

I had ordered calendars from shutterfly for Christmas gifts. The box that they came in was sitting around my craft room. Then one day when I wanted to spray some ink over a stencil, I tried to figure out how to do it without making a mess. So I saw the shutterfly box and opened it up to spray in it.
What I love about using it is:
I'm re-using something I already have
It folds up thin when I'm not using it
It didn't cost me any money
It's the perfect size