I guess I wonder why anyone with a grill would build something new like this. With a standard Weber, you could get some chips smoldering and place your [food] in there and let it go. The temp would not get high and you already have the whole thing in one place. The contraption above looks like they want to make MOAR smoke which might create more heat than you would want so they send the smoke to another vessel. I get it but I don't think that's necessary for what I'm envisioning unless I wanted to make a ton of smoked grape tomatoes.
When you're smoking something like cheese, you need a very cold smoke. Having a fire source in the cooking area produces too much heat. I'll still look for the coffee can generator (been wanting to build that one)