[SUG]: Place stone ore to get the general shape you want. Then grab a stone ax and break it down to "carve it" more precisely.
Pro: Will be able to actually sculpt it pretty well, just using a stone axe (pending ofc on your artistic abilities), and how much time you want to put into it.
Con: If players have a tool in hand (axe, pick, or like), they will see that the stone is already damaged when looking at it up close.
Pro: Stone is already damaged so players can harvest some rock from it quickly, if they are in need of it.
edit: Cool prefab. Looking good.
edit2: If you don't want to do a statue? maybe a indoor fountain? plus it would be a temp place to get some water. <- haha never mind about the fountain sug. I didn't read down far enough