SAN DIEGO — A group of San Diego artists has been working with a variety of materials — scarves, wood, chicken wire, old tires— to build sculptures that tell stories in an empty lot in City Heights. The 12-foot, three-dimensional figures are all part of City Heights’ “Characters,” an open-air gallery inhabiting what has been an empty lot on the corner of University Avenue and Interstate 15. The figures are meant to represent individuals, issues and topics relevant to City Heights. There’s a sculpture of a man made from used tires, mufflers and automotive fluid containers. It is designed to highlight air pollution issues in the community.