Metal beds were used by kings and queens in ancient Egypt. In the 19th century, they became works of art in that they were made by artisans, though for the common man as well as kings. After World War I, they became mass-produced. While still sturdy and strong, the artistry of the pre-war beds was gone. Metal beds are available today in both the old and new style, and can easily hold a double mattress.
Furniture stores can be a source for double beds, these will be in the post World War I, mass-produced ilk. These beds will have a variety of styles and finishes, and can be traditional or contemporary, with wood accents or without. The double metal bed is available as a small double bed for children as well as a four foot by six foot double bed. These metal bedsteads can fit cheap mattresses for an overall savings.
If you prefer metal beds that were made pre-World War I, then you will be able to find them at antique stores. These beds will have the artistry of the metal beds made by hand and will have a variety of accents that have been hand painted. The double beds found at antique stores will be able to fit the new, modern mattress found at mattress stores. Check the condition of the beds before buying them. These beds also work well for memory foam mattresses.
If you prefer to have a custom bed, then you can have a local artisan or a blacksmith to make one for you, or you can make it yourself. When you have the bed made or make it yourself, then you can control the design as well as have the bed made exactly to your specifications. You can use iron from scrap yards or other materials. To add support for the mattress, you might wish to supplement the frame with beech wood slats. As to the finish, you could leave the metal exposed, paint it black in the style of wrought iron, or paint it any colour that you choose. Accents with gold or silver metallic paint can echo the designs of earlier metal beds.