Just a heads up. If you haven't been into a Morrisons store recently you might not have noticed the stainless steel containers that they do.
There are two with SS lids that would make decent billy cans and they also do a set of SS bowls with snap on plastic lids for storage.
They're all pretty cheap but I just bought the small container which is a snug fit around my 10cm Zebra billy.
With a few holes drilled in the bottom and some at the top for skewers to stand the pot on it makes a great hobo stove which takes up virtually no extra space in your bag.