I use a candy tin. Most nicer grocery stores will have an imported candy section. Pick your favorite flavor, enjoy, and use for your PSK. Not waterproof, but a Rangerband like has been suggested would be effective. I have Last Resort PSK that stays in the deepest regions of my backpack. It's a candy tin sealed with a rangerband then secured with duct tape. I let it soak in the sink for about 20 min and all was dry inside.<br><br>Good Luck !!