Scrap Metal can be obtained by harvesting dead Defense Units, Enforcers, Tek Creatures, Tables, Benches or Lampposts in the Sanctuary. It can be used in the same way as Metal would be used. It is harvested most effectively using a Metal Pick. It might be more profitable to have a cage with two of any Tek Creature and have them breed, then kill the baby and harvest the metal. the Tek Creature of choice would likely be two Tek Parasaurs.