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
Step 2: Cut the Bottoms Off the Larger Bottles
Using the hot knife with great care, being conscious of your fingers and such and wearing the vapor mask.
Cut slowly through the plastic bottles, removing the lowermost portions as illustrated.
Step 3: Insert the Tapered Neck Bottle Into the Larger Domed Bottle
Remove the cap from the tapered neck bottle and leave the cap on the large domed bottle.
Slide the large bottle with the tapered neck inside the large domed bottle so they are concentric.
Leave a bit of clearance between the cap of the domed bottle and the opening of the tapered bottle.
Step 4: Remove the Top Portion of the Smaller Bottle
Using the hot knife, wearing the vapor mask, carefully remove the very top portion of the smaller water bottle as illustrated.
Step 5: Cover the Smaller Bottle With the Black Sock and Fill With Water
Slide the black sock onto the bottom of the smaller bottle as illustrated.
Fill it with the water to be distilled.
Step 6: Saturate the White Socks and Put Them Over the Top Bottle
get the white socks soaking wet and then slide them over the top of the two larger bottles
Step 7: Set the Larger Bottles on Top of the Reservoir
Set the larger bottle construction with the wet white sock on top of the lower reservoir.
Step 8: Place in Full Sun and Wait a Very Long Time
Place the completed distiller in full sun on a level surface and leave it for many hours. With any luck, pure distilled water will collect and condense inside the enclosure.
When enough water has collected in the reservoir, remove the top portion cap and pour the distilled water from the reservoir.