I throw in whatever scrap pieces are laying around , as when working with wood I always have plenty of sawdust chips and trimmings let it burn before lead is melted will only help it melt and not out a dime , I also use waste oil , bacon fat or the like as it costs nothing and will lessen the surface tension of the melt . Have not looked for wheel weights around here as the state followed californias lead and banned lead wheel weights , do check for the zinc as it is not worth having in your mix , better to avoid it at the beginning .