That's very slick. Do you think a smaller grain chamber with venting would draft well enough to use an aquarium pump?
I used a tailgating grill as a second chamber on top of a buddy's smoker with a few elbows. It worked fairly well as the temp stayed below 100 but the capacity is limited and there are 0 points for aesthetics on my solution.
I used a couple $1 stainless steel lint traps cut open and sewn on with stranded copper links to hold the grain. It took a jiffy pop looking tin foil ring to get 3lbs of malt to fit under the lid.
Were you able to get a couple hours of smoke with your cocktail shaker or did you have to reload?