Hot1, we saw coops from a crowd called Chook Mowers at the show. He has a very simple fox protection system that you could put on any coop. He's had no reports of failure. It basically involves placing wire around the outside of the coop, about 15 cm deep, as a perimeter. The wire needs to be stiff and wide enough for a fox to start digging but not get through. He says if they can get their paws in and feel the dirt they don't just try further out. His hooks up around the coop so it can be moved, but a stationary coop wouldn't need to do that.