Liquid brick

Lay out a square or other desired shape of hollowed firebricks, all of which have hooks on the inside surface. To these, attach a heavy duty latex membrane which can be inflated like a balloon to the required dimension. Carefuly pour on the liquid brick from the top, and smooth it evenly across the entire membrane, finishing the lower edge to encapsulate the fire bricks. Allow to dry for 2-3 days. If satisfied that the green brick structure is sturdy, slowly release air from the membrane and remove it. The final stage is to add coals to the hollows under the firebricks and let the heat slowly bake its way up the structure for the final firing. Doors and windows can be cut out afterwards in appropriate locations.