What an absolutely fantastic way to secure your hardware cloth! In very cold climates you would want to use metal washers, not plastic ones, because the plastic will get brittle and break easily in the cold.
I like this one but with the interior area higher off the ground for easier cleaning - see side pic of nest boxes in next image. Coop dimensions: 4x4ft for 4-5 chickens, total run area, 4x12 ft (includes under the coop). Use 1x1" welded wire (rabbit wire) to keep predators out (not chicken wire). And larger wire on base to prevent entry by digging (10cmx15cm rectangular wire). Use 'dog door' flaps at roost entrance to trap heat. Add carribeaner to next box flap to prevent egg stealers.