Task was to made a DIY wok burner. Buying one was not attactive option at all, as it's expensive and adds extra complications with gas equipment. Tin-plate cans (large paint cans) were taken as a basis as they have suitable diameter (for wok). Smaller can (combustion chamber in future) perfectly fits larger one.
First version was powered by gasoline blowtorch, which turned to be inefficent - output is too low and it's hard to distribute heat evenly. On that day I ended up with wok on top of brazier, which appeared to be very simple, efficient and mobile solution for culinary use.
Charcoal appeared to be much more convenient and simple to use. Even without active air pumping (on pictures above there's no pump yet) it was more suitable for cooking than a blowtorch, it was verified several times. Once air pump was introduced, there was more than enough heat for a wok. Though 2nd version burner with air pump turned to be very powerful, it was blowing out too many sparks out of combustion chamber, which was not safe at all, as those sparks burned everything (and everyone) around, being spread by wind. High heat also caused another issue - combustion chamber, a tin-plate can was burned so hard there were breaches in tin-plate after an hour of operation, which distorted air flow.
In version 3 sparks issue was resolved - exhaust is directed into opposite side (from cook). More complex exchaust pipe can be added, but field test proven that a simple hole in the can is enough. Combustion chamber is now a reliable 5mm thick 200mm steel pipe, which will not easily burn thru. Tin-plate bottom with smaller holes is disposable and easy to replace. Air pump - cheap 120W air bed electric pump is connected to bottom can with a short piece of 16mm steel pipe fixed to the can with epoxy glue.
For now - it's a perfect burner for me. Video of cooking veggies in 2 minutes, singlehanded :)