Here is a blow-by-blow account of the finishing of the fire-box. Adam covered it in heavy-duty tin foil. He also placed chicken-wire as a reinforcement. He built a wooden frame to go around the fire-box. Some of this frame he covered in black roofing material also, to make it a solid surface.
Then he mixed concrete. He poured the concrete between the fire-box and the frame, to surround the fire-box with concrete. Later, he will take the frame away.
And he mixed concrete. And he mixed. And mixed. He mixed and applied 16 bags of concrete today. He is REALLY worn out! (And he has to preach tomorrow.)
He filled concrete in the sides, and then smoothed it over the top also. This will hold the heat in the fire-box, for a good hot oven.
And of course, no concrete job is done until the creator leaves his signature in it!