Here is my mini busbuddy-type stove, fully functional and very hot (top speed = blueish flame at secondary holes...)
Small instant coffee can, and steel beverage can as a furnace (Aluminium can melted at first full heat trial
I didn't test it in the field yet, but I suspect it's quite delicate to use, needs very little wood and constant adjustment and control...
The hole are a bit big, and air intake too powerful.
But it was fun to make
, and miniaturization works.