So far it's been just a plastic pouch of some kind. I'm fairly new to this PSK-in-my-pocket idea, mostly I've been carrying stuff in my daypack / backpack / whatever-pack of the day.

My present pocket PSK pouch is just a temporary hack, about half of a heavy-duty plastic pouch that was made to hold some food items.

For my bigger backpack PSK I've used a vinyl map case, some zip-lock pouches and other hacks of the day.

The trouble is that I have pretty high demands on the size (as flat as possible, just big enough to hold what I want), but I haven't the time nor money to chase around for the perfect high-tech pouch. So I make do with whatever I can scrounge together from the kitchen and the basement.