PP: OOOHHH! I want to make this too; I'm thinking two inflatable beach balls. Cut the top off of one and fill with concrete mix, then blow the other up inside of that and make sure the concrete sets up ALL around.
~Garden statue~ I'm gonna admit that this is kinda creepy.but I think if it actually turned out that it would be sorta pretty. (Cut the back half of the doll's head off and fill the front piece with cement for a sculptured doll head for your garden.