It saves my back also. These are commercially available or you can improvise. Remember to start with moderate temperatures. You can always add more heat if desired or necessary. High quality briquettes are recommended.
Briquettes provide a long lasting, even heat source and are easier to use than wood coals.
Briquettes will last for about an hour and will need to be replenished if longer cooking times are required. Avoid direct flames on the pot or turn frequently. It is important to remember that these tips are only a guide to help you get started. This is best used for dishes that require even heating. Stacked ovens can become a nightmare if the types of food do not have similar cooking requirements.