Remove the lid and grill from the mini-barbecue and set them aside. If you are using a used mini-barbecue, mix warm water and 1 tsp. of dish soap in a bowl and use a rag to hand-wash the mini-barbecue so it displays nicely. Dry the mini-barbecue by hand thoroughly.
Measure the ceramic planter with a tape measure, then measure the mini-barbecue and subtract this measurement from the size of the ceramic planter to calculate the amount of sand you'll need.
Place the mini-barbecue in the center of the ceramic planter and fill in the surrounding area with sand until it is 3 inches from the top of the mini-barbecue. Sand is a sturdy foundation to hold something in place as it compacts closely together. Sand also works great as a material for a fire pit because it will not burn.
Fill the last 3 inches of the ceramic bowl in with lava rocks. Lava rocks are decorative and have a high heat tolerance.