Somewhere between the normal ziplock foodbags you get and those scary-expensive, heavy duty silicone ones. It's actually for toy storage (tiny pieces of Playmobil etc) but the usual ziplock foodbags get all creased and the zips don't last 2 minutes. I really want something as transparent as possible, easy to open and close and permanent! Can you think of anything that would fit the bill?
God, you know you're old and boring when you're asking about the sturdiness of food bags...!