Actually, I want it to float. I'd like to shape some styrofoam and coat it with that hard cement stuff and paint it. Then place it in my (soon to be built) indoor turtle pond so they can climb out of the water and bask on it. Thoughts?
That might work. If you can source out a dense piece it would float better with the added covering on it. If you go with my source for styrofoam, see if they have anything that is used to protect the ends of leather sofas. Its often VERY dense and I think it would be the ideal piece to work for your project. They're usually big bulky pieces so you would have lots to work on and experiment with.