GregV and odfrank win.

The cardboard ice chest was close to the right size to take top bars, but not quite the right size. I went ahead and did the work to turn it into a pretty nice swarm hive, but it took enough modification that I could have worked from a computer box. It did turn out lighter than a standard deep. Weighed in at 7.1 pounds, and probably most of that was my top bars. You could easily use smaller top bars, but I modified these from ones I already had on hand.

A standard frame didn't quite fit.
Deep frame doesn't fit.jpg
The top bars almost fit, but were just a little too long and needed to be shortened to fit. My top bars are designed to fit the top bar hive, but also are the length and width of a standard frame so I can put them in a Lang box. Once I cut them down until they fit in the swarm hive, they were just long enough to still catch the lip on the lang box. They didn't catch the lip on the top bar hive well, and could slide over enough to fall in. I decided to go with a different approach. I cut them about 1/4 of an inch shorter than necessary to fit the swarm hive. This was short enough to fit entirely inside the Lang box. I will put another strip of wood on top when I remove them from the swarm hive that acts like the tag on a standard Lang frame. That way they fit in the swarm hive now, but I can transfer them to a lang box later once there is comb on them.
top bar with comb.jpgtrimmed down top bars.jpg

Here is what the top bar will look like with the extra strip attached so it fits a lang box
Top bar ready for Lang.jpg