Wow. This looks great. how does the air enter into the air burner from below?
Note the standard HeaterMeter fan attached to the copper tube which comes out through the bottom (left side of picture above). I couldn't find 3/4" flexible copper tube for sale by the foot (only $75 spools), so I used this flexible line that would typically be used in a hot water heater installation (I cut off the the ends which had garden hose style connectors on them). I then hammered the open end of the tube square (inserted electricians pliers into the tube and hammered it flat) so it would fit into the blower, it was a little loose so I added a couple wraps of electrical tape. The other end goes into the center copper T that feeds the "air burner", it was a little loose too, I just worked it over the end of a crescent wrench until it fit tight enough to solder into the T. Copper is soft enough to be worked and shaped easily with hand tools which is why I chose this metal for this project, however, it is a little expensive. You could use another type of tubing/pipe, whatever you can fashion together to fit though your smoker.
Here's a pic of the burn plate removed from the bottom, you can see the square taped over end that goes into the HM blower....
Since I took this picture I have taped off the majority of the third vent hole leaving just enough room for the copper tube to fit through, reducing the natural air flow even further and giving the HM more control over the fire...
Best part about it, beside the solid temperature control, just a tiny piece of paper under one corner hit with a blowtorch for 30 seconds is enough to get the fire going!