I just cut a chunk off (be careful when cutting this stuff!) and stuck some bamboo skewers in it. It doesn't balanca the greatest so you have to evenly distribute the bags.
Not too bad for free. It is pretty unattractive so I will have to find a place to hide it when someone comes over. I would have to make a bazillion of these things to make a dent in that styrafoam I have but it is a start!!!