i'm sure i read it hear somewhere and thought what a good idea:
i have my crampons in two (big size, are they 2.5 or 3 litres of something) coke bottles.
i cut them in both round the dome part, one slots inside the other, crampons fit nice and snug even when i leave them out to size ten, very lightweight. the inside one has a tiny bend in the top. i know what one the outside is as i have put some duct tape around it (perfect bodging gear), and the last roll of the tape i put a bit of copper wire and some cable ties and just laid the tape down round the bottle. keeps the emergency repair kit with the storage container. costs nothing (if you like fizzy drink, which i dont, but someone always does).
not sure weather to drill some little holes in the nipples (yes i did just say that) on the bottomes of the bottoms though, just to let a bit of air get in.