Fly boxes for BIG flies!!
Finally, after searching all over for a box that's 1) big enough to hold a bunch of Buffy- or similar-sized flies, and 2) small enough to shove into the front of my waders, I've discovered it- at You-Do-It Electronics in Newton!!
Part # V501 is a brown plastic box w/ self-hinge, around 4 1/2 x 10", and 1 3/4" deep.
I gooped a couple of strips of foam in at either end, and presto.
While I thought I was getting a bargain at $3.99, there are rumors that they can be gotten even cheaper.