This is about as dirt-cheap of an idea as they come. Hikaru dorodango is the Japanese process of turning mud into perfect polished spheres, a green idea for home decoration featured recently in Craft 'zine that only requires dirt, water, a plastic bag, a soft cloth and a bit of patience. Depending upon the mud you use, you can create white, black, and even red polished spheres. How fun would it be to travel across the nation (or globe) and make a collection of spheres from the soil of your travel destinations? For instruction of how to make your own hikaru dorodango, check out Bruce Gardner's excellent how-to site.