I just bought a peice of driftwood a couple weeks ago it would'ent sink. I'm luckey it was hollow throughout the middle, so anyways I went to sears and bought a 3 pound dumbell I went home all I had to do was drill a little bit of wood out just enough for the weight to fit in nice and tight. My only wonder is if the dumbell could possibly rust guess I'll have to cheak it from time to time.