I think I first read the term “intermediate technology” in the writings of E F Schumacher in the mid-70s, and it made so much sense. Find the achievable scale of industry or machinery that is both affordable and effective, without senselessly clutching onto the latest and most sophisticated, which might not even be the best in many situations.
I read some while back about using the ubiquitous clear water bottle in third world countries for disinfecting water for pennies a gallon. SODIS: Solar Water Disenfection
Another “bright” use is to cut a hole in the sheet metal roof of an african hut, and provide light in dark places. SeeÂ The World’s Cheapest Lightbulb Is Made Of Just A Plastic Bottle | Fast Company