I am just working on this idea. Here I have epoxied a copper flange to an old can of powdered milk and attached 1 metre of old silicone tube. I was catching the water in a Vargo 450 ml (cool lips) titanium mug. I was just cooling the steam with wetted down tea towels. I collected nearly 400 mls in an hour. I need to improve the steam condensation. I will purchase a Platypus hydration tube (as that is what I figure folks will carry – & which is a much lighter weight 102 cm PU tubing) which will hopefully shed heat better.
I will also make up a trough so I can cool nearly all its length with water. I expect I will more than double its output. If you needed to do this in the wild (presumably by the sea) you could make a trough in the sand, line it with your raincoat and fill it with water and keep adding cool water – perhaps carrying it in your shoes. You could also bury the collection cup in wet sand and perhaps cover it with something else to further prevent steam escaping – eg your full Platypus bottle. Doubling output would produce more than 2 litres in 3 hours – enough for a day of low activity – so certainly enough to save your life.
I am imagining adding the flange to your existing billy lid or placing it in an extension ring which sits between billy and lid. Such an extension ring, if I can figure out how to make it adjustable (and fit) would weigh only 15 grams or so and fit with your other cooking things in your billy or pot.
PS: I just made the flange from a piece of copper water pipe using a plumber’s flaring tool. You could cut the flared end from a car’s brake line obtained from an auto wreckers. I used a small piece of ‘Dynasteel Epoxy Putty’ [250C] to attach it. Adding it to your billy/pot would add 5-10 grams and may save your life sometime.
If you are going to add such a (brake) flange to your pot lid or to the side of your frypan lid, you will need to drill a hole that almost exactly matches it, then sand off the surfaces before you apply the Epoxy Putty. If you need to bend the pipe, fill it with sand first. You can plug the pipe with a piece of bent over PU tubing to prevent steam escaping when your are cooking.
Anyone who uses a wood fuel stove such as a Trail Designs Caldera Cone (https://www.traildesigns.com/stoves/caldera-cone-system) or the Bushbuddy Stove (http://bushbuddy.ca/) will have a virtually infinite fuel supply (of driftwood etc) for powering the still.