Sculpin-
I use several different size containers. I have an Altoids tin (as Gardenfish suggests). I also use an old AOL CD holder and a small Plano plastic tackle box. The size I use depends on the size of the flies I expect to get back. Also, as Gardenfish said, it is proper etiquette to send the host extra flies or some other type of goodies. If you are hesitant, check with Steven McGarthwaite (AKA Parnelli) who runs the Beginners Only Swaps. He may have an opening or at least put you on the waiting list. That's how I first started doing swaps. Good luck.

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Elliott W.

I tie flies to give the fish something to laugh about.