Any rock can do the job. Maybe a better rock would be better, a common jar of ordinary beach pebbles could do it for you... Go to a rock store and buy a bunch of fancy but cheap polished stones..and a fancy bottle.. still WAYYYYYYY cheaper than the overpriced nonsense. (as if you are too stupid to fill a jar with rocks?, so they charge $ hundreds $ for the privilidge of doing it for you!)
I have used bricks with a thin layer of rubber on the bottom. Work great. and a whole lot cheaper that some magical overpriced gobbledygook. (and they sell magic bricks too... also $ hundreds $ for what is basically just a damn brick.. or a pile of small rocks!
I have used bricks with a thin layer of rubber on the bottom. Work great. and a whole lot cheaper that some magical overpriced gobbledygook. (and they sell magic bricks too... also $ hundreds $ for what is basically just a damn brick.. or a pile of small rocks!

