While this is more used for decoration, it was used by a local logger's wife to take him his lunches. She told me she would put the ingredients for a hot meal in the various containers and used it over a gas fire. Would it have been easier for her to just fix something and take it to him? Maybe, but I just thought it was a cool yard sale item.
As you can see this one has several compartments and a handle for the bottom pan.
These are mostly used in Asia. Some restaurants used them as take out boxes with a deposit. While mine is thin walled aluminum, today's are double walled stainless steal. Some are very ornate. Some are just three sections, soup, main course and cake.
I guess my dad's love of antiques and unusual rubbed off on me. He had a vast collection, of hand wood working tools, Wild Turkey bottles, Fishing lures and other small items. While I no longer collect. I do enjoy having them and displaying the items I do own.