Here's Manu Arenas' lovely design for the fox's den in "The Gruffalo", a colourconcept by Max Lang and the physical set built by Klaus Morschheuser's fantastic team. More from that sequence here and here.
Some nice drawings below, which Manu did for "The Gruffalo" to illustrate how his design of the stream and rapids would work after the bridge (above) comes loose and falls into the water...