Someone already asked about using it as 3D printing material on the open manufacturing list and 4ndy said:
"If you somehow had an extruder that could use a strip of plastic that
buckles under the slightest push... but even then PET is rubbish for
FDM/FFF printing due to its high shrinkage compared to PLA. Short answer: no."
That's a good point. I wonder if it would be possible to create a print extruder that works for this. It may be that the shrinkage happens before extrusion, such that little or no shrinkage will occur in the print.
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marc/juul