I built one.
I took a 2" square steel tube and cut about 7" off of it and welded it to a 2" flat bar. Drilled a 1" hole in the front side about 2.25" from the plate. Then I cut a 1" square steel tube at a slight angle to allow for exhaust and welded it over the hole. Then I drilled another 1/2" hole about 1/4" up from the plate in the side of the 2" to allow for air draw.
Now this is the tricky part...
The nozzle (1" square tube) is angled to help produce air sucktion from the excaping smoke that is puring out of it, but it doesn't have enough draw to kindle the coals in the pot, so started with a real small hole (1/8" drill) then drilled a nother larger hole (1/4") an angle from the back side toward the end of the exhaust tube to accept a 1/4" tubing that I connected to an aquarium air pump. The key here is hole placement. If it's to far forward, (that is too close toward the exit point) then it just puffs the smoke away, and if its too close to the touch hole (to close to the 2" tube) it will blow the smolder out. when it is positioned approximately 2.34 of the distance of the tube length divided by the total volume of the ID of the 2"tube i.e. length for a chip hopper assuming at least some the volume is filled and therefore is lessened, and figuring that the 1/4" hole is a 4th of the exhaust,
When I tested it the LEDS all flashed and everything, and the buzzers beeped loudly while the voluminous silence of the cold smoke billowed into my smoker. (wrong board for handymen!!)
Anyway, the pro smokers gave me the idea is that it doesn't take a lot of smoke, to smoke things, and any smoke at all is good for smoking, you have to remember, that when you cool smoke, you are stopping its ability to cook, and it is not OK for eating afterward without first cooking it or cooking it first. The chips go down the 2" tube, and the fire is started with an open flame through the hole in the side of the 2" tube. you will need to put a flue over the side hole by drilling an 1/8" hole next to the 1/2" hole and securing a piece of beer can shaped into 1" cover so that it can be raised or lowered to increase or decrease the amount of air that passes through the firebox. I have heard of people trying to create refrigerators that cool compartments of the smoker, but I wasn't trying to build anything that important. I was after efficiency. You might try it.
Hey?!!!? How about hide glue to hold my battery box!!! wow what an epiphany!