I save my used charcoal blocks and find these work well for the oven. The picture shows that the charcoal blocks form three sides of the oven with a fire brick as the base and a fire brick as the back wall. Space the side charcoal blocks far enough apart that a trivet to hold your piece will fit in the oven. Part of the trivet needs to hang off the base fire brick so that you can get the torch under the piece. It's not possible to move the torch under the entire piece; therefore, it may require that you turn the trivet around after the first firing to reach under the other side of the piece. This is not always needed and depends on the size of the piece.