Smelters can be found in most large towns, as well as near many mine entrances.
There are six different materials that can be smelted into Dwarven metal ingots, but looting all of them from Dwemer Ruins will usually be impossible because of their weight. However, if one has the patience to walk throughout a Dwemer ruin, once you leave you can drop enough ingot material to fast travel anywhere you need to place the metal in a secure place. Then simply fast travel back to the ruins and pick up what you can carry, repeat as necessary. (Note: make sure to place the Dwemer metal at the front entrance to the ruins, so that when fast traveling back and forth you do not need to go hunting for treasures that you already looted.)
Due to the ratio between weight and resulting ingots, it is a lot more efficient to collect Small Dwemer Plate Metal, Large Dwemer Plate Metal and Bent Dwemer Scrap Metal, than either of the struts or Solid Dwemer Metal.
Also note that, confusingly, Dwemer Scrap Metal can not be smelted at all.
|Material||Weight||# of Ingots||Weight per Ingot|
|Bent Dwemer Scrap Metal||2||3||0.67|
|Small Dwemer Plate Metal||2||3||0.67|
|Large Dwemer Plate Metal||2||3||0.67|
|Solid Dwemer Metal||25||5||5|
|Large Dwemer Strut||20||3||6.67|
|Large Decorative Dwemer Strut||15||2||7.5|