Just before Halloween I bought two gigantic skulls that glow and issue mist from their eyes (how cool is that?). This got me off my fat idle arse enough to build the first stage of my Valley of the Skulls. But the big skulls needed a waterproof base to stand on. Hence my lakes. The smaller ones are built on cardboard but these two big beauties are actually covered in plastic tablecloth material!
That's an Ogre Tyrant for scale.