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THIS DEVICE RECYCLES PLASTIC WATER BOTTLES INTO 3D PRINTING FILAMENT (AND IT'S OPEN SOURCE)

Plastic water bottles become 3D printer filament, cut into ribbon by stacked bearings instead of blades.

by Reiten Cheng

FULL CAD BOM FIRMWARE DOCS

WorkshopOpen-hardware

Built withSTM323D printing

difficulty
●●●●○
time
a long weekend
license
GPL-3.0
repo
repo FINISHED (NO LONGER SUPPORTED BY THE CREATOR)1,163 stars

WHAT YOU’LL NEED

Videos
1
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COMPAREE VERDICT

The Polyformer cuts a PET water bottle into a continuous ribbon with a cutter made of stacked bearings, so there is nothing to sharpen, then pulls the ribbon through a repurposed 3D-printer hotend that thermoforms it into 1.75 mm filament on a motorised spool. The creator, Reiten Cheng, stopped supporting the project in late 2025, but the files, build guide and Discord community are all still open, and part kits are sold by Triangle Lab and DFH. Two things will catch you early: the printer you use to make the parts must handle over 260 degrees C and must not be PTFE-lined, and the build involves high voltage components plus moderate VOC fumes during extrusion - the project explicitly says to get help from a maker or electrician if you are not confident. Also check the controller: the EBB42 V1.2.1 now shipped in kits is not compatible with the old firmware, so source a V1.2/V1.1 board or be ready to update the firmware. If you print a lot and you have access to a workshop where mains voltage and fumes are not a problem, this is one of the most honest open recycling projects available.

GOOD TO KNOW

  • —All STLs, electronics list, and assembly instructions are in the repository.
  • —Firmware and setup are provided for the kit's EBB42 board (Alexware) and for a legacy Klipper setup.
  • —The project is GPL-3.0 (hardware, software and docs, OSHWA-certified) — you may build, modify and sell it, as long as derivatives stay under the same licence.
  • —The creator stopped supporting the project in late 2025 after three years.
  • —The full BOM is a linked spreadsheet rather than a file in the repository; part kits from Triangle Lab and DFH cover most of it.
  • —You must own or borrow a 3D printer that can print above 260°C and is not PTFE-lined to make the parts.

Parts to buy

5 items

From our check of the build. Exact quantities and part numbers are in the creator’s BOM.

  • Polyformer part kit or the partsFind
  • EBB42 V1.2/V1.1 controllerFind
  • 3D-printer hotend with brass nozzleFind
  • Bearings for the cutterFind
  • Power supply and fastenersFind

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Can I build this?

PrintAll structural parts, including the bottle cutter, carriages, gearbox and main body. The repository provides STLs and STEP CAD files.
BuyThe Polyformer part kit (Triangle Lab or DFH; printed parts not included) or the parts from the BOM: stepper motor and gearbox parts, EBB42 V1.2/V1.1 controller, a 3D-printer hotend with brass nozzle, bearings for the cutter, power supply and fasteners.
ToolsA 3D printer capable of printing above 260°C (not PTFE-lined), basic hand tools, soldering iron, and a workspace rated for mains voltage work.
SkillsIntermediate mechanical assembly, flashing the EBB42 firmware with STM32CubeProgrammer or dfu-util, and confident mains wiring - the project recommends help from a maker or electrician if you have not wired mains before.
TimeA long weekend if you have all the parts and the printer time is not queued; test cuts and calibration add more.
CostModerate; no total is published - check current prices for the Triangle Lab or DFH part kit, plus filament to print the parts.
SafetyMains voltage components and moderate VOC fumes during extrusion. The project advises help from a qualified maker or electrician for the electronics. PET extrusion produces fumes; work in a ventilated space or outdoors.

This build involves mains voltage — for adults comfortable with electrical work only.

Build at your own risk. Projects involve tools, electronics and sometimes mains voltage — follow the creator’s safety notes.

Videos

Community video by Call Me Swal, not produced by the creator.

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Gallery

Start here

Navigation into the creator’s own docs — we don’t rewrite the guide, we route you to the source.

  1. 1.Check your printer can print above 260°C and is not PTFE-lined(If your hotend is PTFE-lined, the PTFE will degrade at the temperatures needed to print the Polyformer parts. An all-metal hotend is required.)
  2. 2.Read the BOM and the assembly guide in the repository, or buy the part kit (The BOM folder and the Andromeda V1.2 assembly guide list what you need; the part kits from Triangle Lab and DFH cover most of it (printed parts not included).)
  3. 3.Print the structural parts and assemble the frame before ordering electronics(This lets you test fit and catch dimensional issues before committing to the full electronics order.)
  4. 4.Get help from a maker or electrician for the mains wiring if you are not confident(The project explicitly recommends this. Mains voltage mistakes are not recoverable.)

Resources

Documentation, files and community threads for this build — we link straight to the original sources and never rehost the creator’s files.

KNOWN ISSUES

  • Mixing hotend parts that do not match the printed meltzone: Polyformer uses a repurposed 3D-printer hotend and brass nozzle, so check the meltzone assembly guide and the BOM before you buy substitutes.
  • Using a PTFE-lined hotend to print the parts. PTFE degrades above 260°C; you must have an all-metal hotend to print the frame safely.
  • Underestimating the fume output during extrusion. PET produces noticeable VOC when melted. Work in a ventilated space or outdoors, not in a closed bedroom.
  • Expecting the filament to match commercial PETG. This is recycled PET, and it behaves differently. Print temperatures and retraction settings will need experimentation.
  • Assuming the project is still actively supported. The creator stopped updating the repository in late 2025. The community Discord is your primary support channel now.

Can I sell the machines I build?

Yes. Polyformer is GPL-3.0 for hardware, software and documentation (OSHWA-certified US002136), so you can sell machines as long as you pass on the same licence and share your modifications.

Does the filament print like commercial PETG?

Not exactly. It is recycled PET from bottles, not commercial PETG, so expect to experiment with temperature and retraction for your printer.

How long does it take to process a batch of bottles?

The project does not publish processing times. You cut each bottle into ribbon with the bearing slicing tool, then the motorised spool pulls it through the hotend on its own; collecting, cleaning and drying the bottles is where most of your time goes.

Is the creator still supporting the project?

No. Reiten Cheng stopped supporting the project in late 2025 after three years. The files and community are still open, but there are no further updates planned.

Community builds

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Discussion1

FROM THE COMPAREE TEAM

Polyformer slices bottles into ribbon with a cutter made of stacked bearings, then thermoforms the ribbon into 1.75 mm filament. What would stop you from building one this weekend?

CompareeTEAM2mo agoedited

Practical notes from our verification: the repository is complete, but the creator stopped supporting the project in late 2025, so the community Discord is now the main place for help. You do not have to source everything yourself: part kits are sold by Triangle Lab and DFH. The single biggest trap is the controller: the README warns that the EBB42 V1.2.1 board now shipped in the kit is not compatible with the old firmware, so either source an EBB42 V1.2 or V1.1 or be ready to help update the firmware. The README also says your printer must be able to print above 260 degrees C and must not be PTFE-lined. Working on it exposes you to high-voltage components and a moderate amount of VOCs, and the creator recommends getting help from a maker or electrician with the electronics. If you meet those requirements, this is one of the most honest open recycling builds available, and it is licensed GPL-3.0. Correction (4 October 2026): we re-checked this page line by line against the project's own repository, documentation and videos, and fixed errors in earlier versions.

Reiten Cheng

Reiten Cheng designed Polyformer as an open-source machine built mostly from 3D-printed parts and common printer components, inspired by Joshua R. Taylor's recreator3d. It won awards including the James Dyson Award international sustainability prize and third place in the Hackaday Prize. Cheng stopped supporting the project in late 2025 after three years, but the repository and Discord community remain open.

GitHub

Star the project on GitHub

DISCLAIMER

  • Comparee is not the author of the projects featured here. All rights to each project belong to its creator — every page links to the original source, and we never host creators’ files.
  • Information is provided without warranty and may become outdated as projects evolve. Prices are indicative bands only — always check the creator’s parts list for current costs.
  • Building and operating any project is at your own responsibility. Protective equipment, safe workshop practice and compliance with local regulations are the builder’s responsibility.
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