The most common materials are definitely 1 (PET) and 5 (PP). Polyethylene Terephthalate makes up many bottles, as well as materials that need to store and are kind of rigid. It is a lightweight, effective material the has many purposes. Polypropylene is also a light material that makes the majority of things. Containers, toys and plastic, reusable cups are just a few. There are also other numbers, but I noticed that these were the most dominant.