Materials
Weighted poly beads are made of polypropylene, a type of plastic polymer. Some other common uses for polypropylene include plastic storage bins and lightweight ropes.
Manufacturers
The most popular brand of weighted poly beads in the United States is Poly-Pellets, made by Fairfield Processing Corporation. They also make Poly-Fil, another popular choice for stuffing dolls.
Uses
Poly beads are used to fill dolls and stuffed animals to give them extra weight and balance. They are usually placed at the bottom of the torso and the feet to give the doll enough weight to sit up on its own.
Techniques
While some crafters leave the poly beads free inside the doll, this can lead to them redistributing across the limbs and torso and undoing the weighted effect. Instead, pour the beads into small pouches made from nylon socks or pantyhose and place these inside the doll or animal.
Warnings
Because poly beads are tiny, they can be easily swallowed by small children if they slip out through a loose seam. This is another reason they should be placed inside nylon pouches when used for stuffing dolls or animals.