Were you thinking 65K BTU wasn't enough to brew outdoors in winter? :-) This shroud was built from a sheet of 4x8' galvanized tin. The slit in front lets us slide the shroud over the keg, leaving the valves exposed. The cut-out on the lid also lets CO2 and steam escape.

Be careful if you construct one of these, the temperature of the shroud can easily exceed 400F! I burnt my fingers on the cover not long after this picture. :-) I later found a pair of lined leather gloves I use when handling the shroud.