The shells iBattz and uNu use as the base of these cases are the kind we almost always stay away from: thin plastic protectors that snap around the sides of the iPhone 5, covering the back while leaving the top and bottom edges fully exposed. uNu’s are available in a number of colors, while iBattz’s includes two total black or white shells, each with a tribal pattern printed on it. The shape of both companies’ shells is literally…