Smartylamps are made from sheets of polypropylene (PP) Polypropylene (PP), also known as polypropene, is a thermoplastic polymer used in a wide variety of applications including packaging and labeling, textiles (e.g., ropes, thermal underwear and carpets), stationery, plastic parts and reusable containers of various types, laboratory equipment, loudspeakers, automotive components, and polymer banknotes. An addition polymer made from the monomer propylene, it is rugged and unusually resistant to many chemical solvents, bases and acids Polypropylene is recyclable and has the number "5" as its resin identification code: the number 5 surrounded by a recycling symbol, with the letters "P P" below. As polypropylene is resistant to fatigue, most plastic living hinges, such as those on flip-top bottles, are made from this material. This material is often chosen for its resistance to corrosion and chemical leaching, its resilience against most forms of physical damage, including impact and freezing, its environmental benefits, and its ability to be joined by heat fusion rather than gluing. The availability of sheet polypropylene has provided an opportunity for the use of the material by designers. The light-weight, durable, and colorful plastic makes an ideal medium for the creation of light shades, and a number of designs have been developed using interlocking sections to create elaborate designs. Source - http://en.wikipedia.org/wiki/Polypropylene