I built the heaters from parts obtained from friends.
The flame spreader came from a forty gallon hot water heater. The orifice is a 1/2" brass cap with a 0.065" hole drilled into the end.
The valve assembly was removed from an old furnace. The safety features of the pilot/thermocouple makes this a nice setup. To turn the flame on you apply 12-24 volts AC.