This is how most of the world’s plastic products are made, from car body panels to bottle lids. It is also used for glass and metals. The material is heated and forced into a cavity mould made of metal, where it cools and hardens. The moulds can be reused thousands of times which makes it ideal for mass production. The picture is showing one side of a comb mould.
Image source: https://sc02.alicdn.com/kf/HTB14sGpJXXXXXX0XFXXq6xXFXXXh/China-Factory-Plastic-Comb-Making-Injection-Mold.jpg
Process: injection moulding