Construct out of ½” inch hardware cloth or welded wireCover vents with ¼” to ½” wire meshSecure, tight-fitting lidPrevent rats from burrowing under the compost. Suggestions:¼” to ½” wire mesh over a wooden palletDig out the soil and lay 3 to 4 inches of coarse gravel and ¼” to ½” galvanized hardware clothSolid foundation of concrete or patio stones