Heh, I just wrote up a post in another thread about my great new find: Old laptop bag. In my black leather laptop bag (it ain't a slim one!), I can fit seven handguns, fully protected. Wrap each one in a small hand towel or old t-shirt, each is in a different and fully zipped compartment.
I've tried numerous ways to haul multiple handguns on range day, but this latest trick I'm using is probably the best one yet.
If you don't have an old laptop bag, see if you can find an old one at a used computer store or even a resale or Goodwill type of shop. If not, a new lap top bag probably costs less than some of the fancy "made for handgun" boxes.