Ok,there seems to be a bit of interest in these.Firstly,you can use either stainless or mild steel for construction,I use stainless coz I got plenty.
#1 find some 2" tube and cut it about 150mm long,then cut 2 pieces off the bottom at an angle...see pic
#2 next take a piece of pipe about 13mm,doesn't have to be exact,any piece will do,about 400mm long and weld up one end,make sure you weld it up properly as this will have high pressure gas going through it,I normally hit it with the mig then give it a hit with the tig to make sure it's sealed
#3 next thing is pretty important,take a 1.5mm drill bit,it HAS to be 1.5,any bigger and you get too much yellow flame which will cover the bottom of the boiler with soot and shit.Drill a hole 60-70mm back from the sealed end,if using staino make sure you use cobalt drill bits or make sure you have a couple of dozen normal drill bits on hand
#4 find a bit of pipe about 8mm ID and weld itaround the hole you just drilled,try to get the hole in the cente but don't worry if it's a bit off centre
#5 next weld the piece of 2" pipe over the piece you just welded on
#6 next thing is to get a male gas fitting and weld it to the open end off the pipe
#7 almost finished,find a couple of off cuts and weld them to the main pipe to make the whole lot stable
#8 go to the gas shop or camping stow and grab a high pressure regulator and hose and if you can spring for a needle valve do so as it allows for finer control of heat.When you get home hook it all up,turn on gas and spray the end that you sealed with some detergent and water to make sure that it's sealed properly.
All done fellas
Gas usage isn't as bad as you might think,I get nearly 4 x 200l stripping runs out of a 8.5kg bottle.will post some more pics tomorrow of one that I built the other weekend that I incorporated into a stand to hold a keg,look and turned out pretty cool and worked a treat