polystyrene-based packing peanuts were developed and patented by tektronix inc. they were made commercially available circa 1965 by dow chemical. originally made from 100% virgin polystyrene resin, peanuts made from 100% recycled polystyrene have been commercially available since the mid-90s. the color and shape sometimes indicate what it is made of and who made it. often green is 70% or possibly more recycled polystyrene, white is 70% or more virgin resin and pink means an antistatic agent has been applied; although there are some variations. the most common shapes are similar to a "s", "figure 8" or "w". foam peanuts are very light (usually around 3 grams per litre/0.17 to 0.2 lb per cu ft) and easy to use.