We had this problem on the trip we are currently on. I did find a solution though.
There is a pin store right next to the monorail exit in Downtown Disney. They have a pouch with a clip on it for sale for $4 I think. You can clip that right onto any of the pin lanyards found throughout DL. It has the plastic zipper top to waterproof whatever you put inside and it's much nicer (easier to get into it with the "zipper") than the other plastic pouches. The regular plastic pouches require you to squeeze the two sides together like the old ziplock bags to seal it up. They can be difficult to seperate sometimes, especially for little kids. The ones in the pin store by the monorail have the white plastic "zipper". You just slide it accross the pouch and it easily opens/closes it.
Even if you don't purchase one now, it's good to know there sealable replacement pouches available. We have had a couple break and had to replace them.