Basics

An Abreviation for Polyethylene terephthalate
Also commonly abbreviated PET, PETE, or the obsolete PETP or PET-P\
Commonly found in water bottles and thermoformed containers
It is thus a good source for recycled plastic usage
Tech for Trade have developed the Thunderhead Extruder almost specifically for this plastic

Potential Issues

From Wikipedia:
- "PET is hygroscopic, meaning that it absorbs water from its surroundings. However, when this "damp" PET is then heated, the water hydrolyzes the PET, decreasing its resilience. Thus, before the resin can be processed in a molding machine, it must be dried. Drying is achieved through the use of a desiccant or dryers before the PET is fed into the processing equipment."
The solution thus is an Open Source Filament Dry Box