Mightypets - Exercise Pens for Pets - page 1 of 7
Those are examples, but when you're not home you can put him in it so he's not free to roam the house as he pleases. Gizmo goes in a crate, however with my next pet I'd prefer an x pen simply because you can add a pee pad.
But I definitely wouldn't let him have free reign over the house if he's doing that to your walls.