PEEPER on Instagram: "Tennis balls are made through a careful process that combines rubber molding and fabric covering. First, natural and synthetic rubbers are mixed and molded into two half- shells. These shells are placed together with a glue-like adhesive and then pressurized with air to give the ball its bounce. The sealed rubber core is covered with a layer of adhesive, and two pieces of felt, usually made from wool and nylon, are carefully cut into shapes that fit around the ball. The fel