LOL, a belly band is just a thin band of paper around something - a box, an invitation, etc. I've just been stacking my items neatly and wrapping the band of paper around them to keep them together. With my larger items, you can still see all of the individual designs in a set, but with some of the smaller ones you can't really :-(
I like the idea of leaving at least one of each type of thing un-banded so people can see what it looks like in more detail.