I know this is probably not a new idea, but lately I've seen this cutie pop up several places, and I can't help falling in love with it...
And it's quite simple to make as well; cut a mouth on the tennis ball and add a couple of eyes (eg. with a marker, or buy roll eyes at your local hobby store). To be able to hang it, you need something that can stick to your wall. You can use Velcro, strong tape, something with suction etc. Give it a try, and you'll have a little hanger for yourself!
