The refractory material is cat litter sand and little horse maneure. It took forever to teach the horse to use a litter box.... 3/4 tuyer. 2x6 wood. I didn't have enough adobe to fill the whole box so the far side is sand for about 4 " . fired it up today and shaped some angle iron which I used to mount my anvil. A good day. It heated 1/2 rebar yellow about 3-4 inches no problem.I used a hair dryer today but I did find a double action mattress pump which I'll play with later. Now that I have a workable set up I plan on forging 5 or 6 rebar snails for hammer practice.