>So, the same basic principle could work with an observation hive right? I plan to make my own observation hive this weekend. If I just let the bees draw comb and then every so often remove a frame of brood and put it in a hive and replace the frame with foundation...that should keep them small. Do I have this right?
Basically, yes. The only catch is that the field bees keep going back to the old hive so it's hard to cut the population down quickly by just taking brood combs. That cuts it down eventually. Therefore, you need to plan ahead to keep the population under control, without doing too much.
In case you're not following me, you take a frame of brood and bees and put it in another hive. The nurse bees stay. The brood, of course is now gone from the nuc or observation hive, but the field bees will fly back home. This makes it a little harder than you'd think at first to keep a constant population. But basically as long as you keep stealing brood at the appropriate speed, you can keep the population reasonably stable.