Update: NEVERMIND - this idea did not work out. I will have to rethink it and try again some day
Here is a design for an inexpensive and easy to make portable solar water distiller.
It works by allowing evaporated water to collect in a reservoir created by the space between two concentric plastic bottles.
The reservoir is another plastic bottle covered in a black colored fabric to make it hotter than the surrounding structure.
The collector is kept at a lower temperature using evaporative cooling.
The temperature differential created by the evaporated cooling should allow the condensation process to happen a little faster than it would without it.
Step 1: materials
You will need three plastic bottles. Two that have roughly the same diameter around the widest part. One of those should have a tapering neck, much like a wine bottle. I couldn't find plastic wine bottles, though I have heard that they are being introduced in Europe. So I went with the arrowhead sparkling water bottle shown. The third plastic bottle should have a smaller diameter around the widest part.
a hot knife for cutting plastic
a vapour mask to avoid fumes
one or more white socks
one or more black socks