Convert plastic bottles into 3D printer filament

I have followed various open source projects to produce filament this way for a few years, starting from a facebook group.<p>It is called &quot;pultrusion&quot;. A key property of PET plastic is that it is not infinitely re-meltable, it gets more brittle each time. If you melt bottles to form filament, then melt it again when printing, those two re-melts are too much.<p>But, you can heat it enough to soften it without truly melting it -- so it does not loose strength -- and pull it through a heated nozzle, that kind of wraps the little strip around into a tube, sometimes with a small hollow center like a straw.<p>There is then one full melt left in the plastic&#x27;s life to allow a 3D printing.<p>You might have to adjust for the filament being hollow and extrude a bit more.<p>You also get a filament with a shorter length, just the plastic from one bottle, because joining the filaments is finicky and no one seems to have come up with a reliable way yet.<p>In spite of all this, it&#x27;s really appealing because getting one more human use out of the vast volume of PET bottles that are thrown away seems really useful.<p>Note, that the strips that you cut the bottles into, are useful by themselves. There are a series of youtube videos by a Russian guy building a log cabin in the woods, and he utilizes those strips extensively -- if you use them to tie things together, you can pour hot water on them or heat them with a flame and they will shrink and stick to themselves, making a really strong joint.

Maybe I&#x27;m an idiot, but I was really struggling to understand how this worked from the website, which seems to have no photos or video of it actually operating.<p>I searched youtube and found a youtube short of it being used.<p>First you have to use another small machine to slice up a plastic bottle into a spool of roughly formed plastic spaghetti. Then you feed it through the nozzle on this machine to draw it into a properly formed filament.<p>Having to slice up every plastic bottle you want to run through it by hand seems like a cost to using it in any kind of bulk (I originally was trying to work out if it melted them down which would alleviate that).

There are a variety of open source projects to do this.<p>One thing to consider is that PET isn&#x27;t the same as PETG, and may require changes when printing, and possibly additional ventilation<p><a href="https:&#x2F;&#x2F;all3dp.com&#x2F;2&#x2F;pet-vs-petg-differences-simply-explained&#x2F;" rel="nofollow">https:&#x2F;&#x2F;all3dp.com&#x2F;2&#x2F;pet-vs-petg-differences-simply-explaine...</a>

This is a really cool project, but obviously don&#x27;t expect the same quality of filament as a big company. The width will vary across the length, leading to inconsistencies in the final part.

Looks interesting. Just bought a tiny 3D printer and had to by my first spools of filament after running out of the sample spool that cam with the printer. I do not think I will go this way (I am not printing much) but it is nice to see this sort of thing.<p>Also from the link (I just thought it was a little funny and answered a question I had)<p>&gt; <i>&quot;Do all plastic bottles work?<p>Yes, as long as the bottle is made of PET. But the bigger the bottle the more filament can be made per bottle! Plus don’t forget, any colour of bottle will work!</i>

Problem is, I paid a refundable deposit on the bottles, as an incentive for returning them.<p>If I lose 10 cents by turning a 500 ml bottle into filament, will I get at least 10 cents worth of filament out of it?