We used a metal 55 gal barrel, cut in half, placed on top the cinder blocks. Dig down a little to set the fire. A nice hot fire underneath brings it to temp, then adjust to keep at temp for appropriate time. A scrap of plywood for a lid worked well. It fit 16 - half gallon bottles, or 20 something quarts. Cannot set the bottles on the bottom of the barrel, usually built a platform few inches high, from pallets or whatever. It does have to allow water to move through. Takes tending, but worked well for many years, until a neighbor noticed and felt we were working too hard, brought over his propane cooker that we set the barrel on. Same set up, more efficient, except couldn't cook dinner in the coals. Sometimes the wind does blow, so we had a peice of corrugated tin or plywood to lean against the cooking barrel to protect the fire from the wind and regulate the temperature.
