You can easily freeze the prepared arancini balls and then air fry or deep fry them when ready. Once the Rice balls are shaped and breaded, place them on a tray and freeze it for couple of hours. They would become hard by then. Transfer the frozen balls into a freezer bag and freeze them for about 3 months. When ready, place the balls directly on to the basket of air fryer and cook. It might take longer than mentioned to air fry the Arancini when starting from frozen.