Extrusion

Extrusion is a process where a thermoplastic is squeezed through a shaped hole in a metal plate to produce long pieces with an unchanging cross-section.

The tooling for extrusion is typically inexpensive compared to other processes, so if your part has a constant cross-section, extruded plastic may be the best way to make it.

The weather strip under a door is one product made by extrusion.