Two interesting student projects:
Veronica Santos and Julia Parreiras from Belo Horizonte, Brazil make solar water purifiers using recycled plastic bottles and snack food bags turned inside out. The mylar bags are concentrators and the bottles are PET plastic, one side painted black to absorb more heat. They found that PET had more UV transmittance and stood up better to long term use.
Here's my own recycled solar cooker using snack food [popcorn] bags, a plastic cake box, and a dark saucepan.
Savannah College of Art and Design have been working on a homeless sleeping project, building three different models:
sleep shelter based upon a folding lawn chair
privacy screen for homeless shelter bunks
privacy tent for transitional housing bed