i have built a couple of them, the simplest was a shallow tote and an air stone, when the bubbles pop the surface they kind of mist the stalks. I also have one in a 13 gallon tote with a pump and misters, I dont like the plastic misters so I am upgrading to brass ones preinstalled in a coupling. I think when I tap the holes for the plastic ones the chips drop in and eventually plug them up. 

In the winter I will let it run 24/7 and in the summer I put on a timer and run a minute on 10 minutes off, with or without a humidity dome doesnt seem to matter but I mist the leaves once or twice a day. 7-10 days and I usually see roots so its a little faster for me than using rapid rooters or Rock Wool. I have tried it with and without Azo's and all I can say Azo's does is make a mess and any gel you put on the cuttings washes off in a day or less so now I just use PH water and nothing else.