Tin can lids as shingles on this stylish chicken coop. Don't have to have a chicken coop to use this idea. Doghouse comes to mind. I have a side-cut can opener so that would even eliminate sharp edges.
Whitewashing the chicken coop - Classic lime whitewash disinfects, repels insects, and preserves by sealing surfaces and wicking up water. It dries to an opaque white that beautifully reflects light to brighten up dim spaces.