The 'plan' sort of evolved as I succeeded or failed in finding the materials that seemed suitable, so i can't provide a plan, as such. Burnout ovens can be simple or complex, I suppose. The principle of the things seems to be to let a draft of air into a hot box, and out again, carrying away water vapor and other gasses, while maintaining some control over the temperature. My search for a cheap heat-insulator in sheet form brought me to a hardware outlet. What caught my eye was the fire-resistant sheet rock.
Wires exit through the back.
The floor was then layed. Trim with a grinder to fit . Drilled a hole for wax drainage near the floor center. The ceiling is also hard brick splits. It rests on the side walls.