The Polyformer is a 3D printer filament extruder created for people living in 3rd world countries with limited access to affordable filament. It allows you to recycle PET plastic from beverage containers by cutting them into a ribbon and feeding the ribbon through a heated extrusion nozzle.
I've seen people try melting the parts in a sheet tray, so they can shred the thin slab - I was focused on PLA+ which I read degrades in quality with each time it's melted, so I wasn't sure adding an extra time would be a good idea. I should revisit this project at some point though