With most of us throwing away PET in the form of Plastic Bottles it could be simple to use them in your printer. Unfortunately I do not have enough hours in the day but one or more of you may like to try this out. Its a concept an idea that would solve the problems of irregularities caused when using flaked or shredded PET through an Auger setup caused by irregularities of size air gaps and speed of feed, this method converting flat or square input to round is theoretically simpler.
Step one: Turn the bottle into PET string as demonstrated by this guy.
A printed version lifted from the comments thanks faggahz, I am sure most of this project exists in one form or another if it can be put together.
Step two: A print head that can be fed by flat string extruding filament in 1.75 or 3mm format, it should be easy enough to overlap short sections to produce continuous filament. Also feeding in short lengths of filament left on reels to prevent waste or create multi color filament would be possible using same method.
Step three: Link step one and two so that the motor feeding the extruder provides the power to strip the bottles a little work preparing and loading the bottles one after the other but free filament and recycling at its best.
Let us know if you try this I will get A Round TUIT sometime but work interferes with play to much at the moment so
Calibration 2020.stl as would not let me publish without a download