What are glow sticks made out of?

Answer 1

Glow sticks are generally made of a fairly tough but flexible translucent outer casing of plastic, and an inner capsule of thin glass. The pair of chemicals that are responsible for the chemiluminescence are held inside and are kept separated until the glow stick is deployed. One of the chemicals is inside the glass capsule, and the other is "around" it inside the plastic case.

The idea is to get one of the chemicals needed to make the "glow" isolated inside the plastic case, and then allow the other chemical to be "around" the glass capsule and inside the plastic. That way when someone bends the plastic case or strikes it sharply on a hard surface, the glass capsule will break safely inside and release the chemical it held. The two chemicals then combine and the chemical reaction produces light.