I got those metal cannister-vases at Walmart a couple years ago. They were in the kitchen section, so I think they were intended for storing spatulas and big cooking spoons on the countertop. I think they are great for whistles because of the ventilation holes, so your whistles can dry more quickly after use.
I had some round cardboard coasters that I cut a little to fit inside the bottom, to keep the metal bottom from possibly scratching the whistles. You could use a piece cut from a handy-wipe sponge wipe thing too. :)
There's whistles in the jar.