I have just experimented a little bit with a 14cm Zebra billy can and it looks like you can use it to distill fresh water from salt water, if you ever need to.
You need only the billy, a cup which fits inside and something to raise the cup inside the billy. I used an empty tin can, with a hole punched into the bottom so it does not swim, because of the air bubble.
The setup is like that:
Put the empty tin can in the billy, put the cup (I used a 0,5l metal cup) on it and pour some dirty or salted water inside (i just used table salt) so it does not touch the cup. Put the lid on and boil away.
The lid has that indentation (under the grip) where I poured some cold water. The idea was that water would condense on the lid and then run on the indentation and then in the cup. I let it boil for 10-15 minutes and had a small sip of distilled water inside.
A lot of vapor was escaping under the lid, but still it worked. You would have to run it the whole time to have some useful amount of water, but it works.