I had a go at making a tin can spirit burner after seeing an ingenious design by an Australian bloke on Youtube. I've never taken it camping but I did try it out in the back garden - boils water very fast (even in a saucepan weighing over a kilo) but runs out of fuel quite fast too. No flame adjustment.
The fuel in the bottom of the can is lit to prime - the stove warms up, the fuel vaporises to be burnt off at the top of the can. The pan rests directly on the top of the can and air is drawn in through the holes at the bottom. The top slots for the flame are cut on the diagonal so that the flame ignites all the way round when you light it (otherwise you have to light it all the way around).
Here's a photo, taken as the light was going so that the flame showed up better.
I've got a metal canister (without lid) which can be used to snuff the flame or possibly to decant unused fuel back to the fuel bottle (I haven't tried this but it would not be possible to do it straight from the "stove" because of all the holes. The stove, snuffer and fuel bottle all stack together: