Corrugated Scrap is the large, metal sheets with a wavy shape to it (hence corrugated). This cant be crafted, it can only be found along the shorelines or within crates etc. Once you have collected plenty, you need either a Crude or Refined Hammer, then go into the crafting menu and craft furniture out of the metal. Note that foundations, walls and floors do not count as furniture, you want to make things like tables or chairs.
Also, the recipe doesnt have to be solely Corrugated Scrap, it only needs it as an ingredient.