Take one quite large bucket, the size of the sort used for beer brewing. Near the top, drill two holes diametrically opposed. Take a wooden rod of two inches or so diameter, bolt in place across the top so that it freely spins. Build a ramp or similar, part fill with water, and smear some peanut butter or other bait on the centre of the rod. Retire and dispose of formerly twitchy nosed corpses at your leisure.