Not sure what exactly you are looking for in your OP, but I use a Smoke Daddy on my WSM18.5, and it's great. Pellets are definitely better then chips for burn time, but reloading isn't a major ordeal. Here's another thread about them that I see has new responses since I stopped following it, but maybe it'll help? ANd seriously, the chimney is awesome!
http://tvwbb.com/showthread.php?33946-Anybody-use-a-Smoke-Daddy-Cold-Smoker&highlight=smoke+daddy
This might be a little too simple for what you have in mind but it will do the job in either a kettle or a WSM and keep your temps where they need to be for cold smoking.
http://www.youtube.com/watch?v=EWmVcyWYXnI
Look into A-Maze-N Products pellet cold smokers. Great buy for the $, EXCELLENT actually. I have the Medium Tube and the 5X8 (If I recall correctly). During cool weather they don't create enough heat to move the temps very much. They run on pellets, for 5 and 11'ish hour respectively. Creosote free, perfect smoke. Here in Sunny AZ, I could keep temps below 70 deg with the highs hovering around the mid 60's. Did a few belly bacons and then fell in love with Canadian Bacon. I'll have to wait for cooler weather to get to cold smoking again.