the answer is yes I have made one, and it did work, I was not exceptional pleased with it tho,
I had used my torch, propane and oxygen, and used hose clamps to clamp it to a additional handle,
then used a back flash unit similar to what they are doing and used a BBQ grill igniter, and a spark plug threaded into a holder shaped similar to there made out of some exhaust tube fittings, and some 1/8" plate for the rear welded a metric nut on for the spark plug, (the igniter was not Ideal but did or would work),
oh and I used an air gun nozzle for my flow control ,
use the torch body, a welding tip (cut off the tip end) section of hose, then on to 1/4 pipe, then the air blow gun, and then 1/8" pipe, and about a foot of 1/8" pipe the flash back arrestor, and then more pipe, a ball valve if I am remembering correctly, between the flash arrestor and the nozzle, and the nozzle, and the unit was supported by a piece of conduit or small square tubing, as the 1/8" and 1/4" pipe is not enough. (now I am going by memory so my description may have missed something),
you can go to Google patents, and down load the original patents on the unit, I think put in the original guys name is how I found it.
Google Patents I do not know if the patent number is listed in the web site or not.
the torch body was a little small on the unit I tried, and tool a long time to fill, the BBQ lighter was minimal in striking the arc to light the mixture, and it (either do to the fact I was not filling long enough or the tunnels were that extensive my kill ratio was not that noticeable) I was using on prairie rats, (dog), they had take over about 80 acres of pasture, and holes were about ever 10' so it was a very difficult job, I finally went to a different method which seemed to be more effective, and I was using large bottles of O2 but I probly spent $200 in oxygen and my success was not that noticeable,
may be on pocket gophers the story would be different as that was what it was intended for.
the flash suppressor, in my opinion this is a necessary item,
FLASH ARRESTOR Series 8491
other wise I do think you could have metal pieces flying at you or blow up the air gun in your hand,
get a chain saw type hard hat and the hearing protection and face shield,
the concussion from it gets wearing on you, yes it is fun the first few times but dragging hoses and the shock from it, it turns into a job in a hurry,