I'm still not clear on how you expect the straw - which is going to cross over your fire on it's way to the cooling tin - from catching on fire and / or melting into a useless glob of plastic. Presuming that you solve somehow (perhaps you could use your foil to create a heat shield), you still will have a very limited boiling chamber and a difficult refill cycle.

Let's continue this discussion anyway I am sure we can figure out a design that will be fun to try! Please specify the exact materials. e.g. what is the straw in this design made of and where did you procure it? How large are these PSK tins? Are we talking about two altoids containers? If you have a bunch of foil you may be able to short the design a bit.

Let's try a bit of ASCII drawing
<pre><font class="small">code:</font><hr>

_____
__ __
__ __
- -
| |
| | <- foil dome
| | | |
|_| | | |_==== <- collecting straw
| |
|________________| <- foil or PSK pan

</pre><hr>
If you constructed something like this and place your outlet on the bottom of the curled under portion of the foil dome as shown you might be able to heat the side of the pan away from the straw. Perhaps you could use a small aluminum whistle as the start of the collecting straw and keep the plastic out of the fire that way. A construct like this would allow you to create a small still from a single PSK as the dome will be the condenser and the collecting straw could drain directly into your container.