See it in action! Files all available on Printables  https://www.printables.com/model/221589-motorized-plastic-bottle-string-slicer

I figured out a way to make a really simple 3D print that pops on to the end of a cheap motorized rotary cutter (WORX WX081L 4V ZipSnip Cordless Electric Scissors  ) (this is the kind lots of people use to  quickly slice up boxes)

Challenge:

No matter where you are in the world, you probably see plastic bottles all over the place. They are made from PET plastic which is super neat and useful (hence its ubiquity), but also ends up as garbage all around the world, clogged ecosystems and turning into harmful microplastics.

So people try to find ways to turn trash into other useful things to prevent them from ending up immediately right back in the environment.

PET doesn't really melt well like other thermoplastics like HDPE or PP, so one thing people have been doing with PET bottles is turning them into string! There are lots of 3D printable jigs where you just insert a razor blade and they help you turn bottles into a nice spool of PET string. the String actually acts like heat-shrink too, and can be wrapped around stuff and heated for a nice tight fit!

I have tried many of these manual jigs though, and they end up being really tricky to work with if you aren't using the same type of plastic bottle over and over. they get caught, uneven, some snap, or some the plastic is just to thick to cut through easily with the razor.

The solution here is using the nice motorized blade to help cut through whatever consistently!

As a bonus the current model is set to make 8mm slices which is what feeds into Joshua Taylor's amazing http://recreator3d.com/ (so you can go from bottles to 3D printer filament!)