Start from what a predator can actually do
Foxes bite through light chicken wire, lever at loose panel edges, and dig under a run in minutes. Raccoons and similar climbers work latches and lift unsecured lids, and a determined dog can shoulder a weak door. Predator-proofing therefore means removing flex, gaps, and lift everywhere, not adding one impressive lock to an otherwise flimsy structure. Walk around the hutch and run pushing, pulling, and rattling every panel as a predator would, at rabbit height and below, and treat anything that moves, bends, or shows daylight at a joint as a job to fix before the rabbits spend another night outside.
Mesh, frames, and fixings that hold
Cover every opening with strong welded mesh with holes small enough that a rabbit cannot push its head through and a predator cannot reach a paw in, fixed with screws and washers or heavy staples into solid timber rather than into thin batten. Replace any chicken wire already on the run, since its twisted joints unravel once bitten. Doors and lids need proper bolts or latches that require two movements to open, positioned where a paw cannot reach through the mesh to work them, and hinges should be screwed, not pinned. The sleeping box deserves the thickest timber and the most secure door in the setup, because it is the last refuge; many owners lock rabbits into that box overnight when the wider run cannot be made fully dig-proof.
Stop the digging, in both directions
Lay a mesh skirt around the outside of the run, pinned flat to the ground and extending outward, or bury mesh below the turf line, so an animal digging at the fence line meets wire instead of soil. The same barrier stops your rabbits digging out during a long afternoon in the run, which matters because a rabbit who can tunnel out can also be tunnelled in to. On hard standing, bolt a mesh floor beneath bedding or provide solid flooring sections so rabbits rest on something comfortable while nothing can come up from below. Check paving edges and corners where a skirt can lift, and weigh or pin any section that curls.
Position, routine, and the weekly check
Site the hutch where you pass it often and can see it from the house, away from fences and bins that give a climbing predator a launch point, and clear long grass around the run so nothing approaches unseen. Bring food waste and fallen bird seed away from the area, since both draw night visitors. Once a week, inspect for chewed timber, rusting mesh, loosened screws, and fresh digging, and repair small damage immediately; predators revisit places where they once nearly succeeded. After storms, check again, because wind works fixings loose and shifts skirts.
A backstop for the day something still goes wrong
Good proofing makes an escape unlikely, but a startled rabbit can bolt during cleaning or a door can be left unbolted by a visitor. Make sure anyone helping with the hutch knows the locking routine, and keep a recent photo of each rabbit where you can reach it quickly. On KinsLe, a profile carries the Lost Pet Alert System at no cost, the missing rabbit appears as a map entry, and whoever finds the rabbit can send its owner a direct message.