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Sustainability winner

Polyformer - Plastic Bottles to Filament in Rwanda

An open-source machine that recycles waste plastics into 3D printer filament.

  • The Polyformer.

  • The Polyformer is an open-source machine that recycles plastic bottles into 3D printer filament.

    The Polyformer is an open-source machine that recycles plastic bottles into 3D printer filament.

  • Labelled diagram that shows all design features of Polyformer (extruder, bottle cutter, joiner).

  • 3D printed parts made from recycled filament. The bottle plastic used for each print are specified.

  • Sketches from design iterations of Polyformer.

  • Prototype iterations for the bottle cutter. We made sure to optimize every feature of this project.

What it does

Polyformer is a machine that recycles plastic bottles into 3D printer filament. The device reduces plastic consumption, while also producing 3D printer filament at low costs. The open-source machine has already been built in several countries worldwide.

Your inspiration

While working at a makerspace in Rwanda, we learned that many locals couldn’t use the makerspace's 3D printers; due to the high price of importing filament to the country. We also observed the lack of available infrastructure to recycle plastic bottles in Rwanda. Thus, we felt we could solve two problems at once, by building a machine that recycled plastic waste into 3D printer filament for the makerspace. With our machine, makers in Rwanda have easy access to cheap high-quality printer filament. This empowers them to use the makerspace's 3D printers more frequently and iterate on their design projects more often!

How it works

To use a Polyformer, a user must first find a plastic bottle that they would like to recycle. Then, the user cuts the plastic bottle into a long continuous strip; using our custom easy-to-use bottle cutter mechanism. Finally, the user feeds the plastic strip into the Polyformer extruder. The hot end of the extruder will thermoform the strip into 1.75mm filament as it goes through the brass nozzle. After the filament is extruded from the nozzle, it passes through several vents which quickly air cool the plastic. The cooled filament is then wrapped around the spool; which is driven internally by a NEMA stepper motor and 3d printed cycloidal geartrain. With our quick release feature, a user can effortlessly remove the filament spool from the Polyformer and insert it into any 3D printer! A standard 2L plastic bottle produces ~20m of filament. For large print jobs, our joiner mechanism can be used to fuse short segments of filament into a longer length

Design process

Polyformer was designed to meet the following design criteria: 1. The machine should use primarily 3D-printed parts to reduce the need for sourcing components, as many items aren’t available around the world. 2. The parts should be designed for ease-of-print, avoiding as many supports and post-processing steps as possible. 3. The machine should be compact so that it can fit in many workshops. 4. The machine should be easy to put together and not confusing to assemble. 5. The architecture should be easily configurable to allow expansions and modifications by users. After creating a rough prototype to validate the proof of concept, we proceeded to take a step back to assess the key components of the machine and discuss ways to optimize them. We built cardboard models and prototypes to help understand the scale and accessibility of all the user’s touch points. Eventually, we landed on the vertical L architecture that enables users to easily access both the extruder on the front and the spool on the back of the machine, while the electronics are sitting underneath to save space. Then, we proceeded on an iterative process of 3D printing-testing-analyzing-modifying the machine. In total, we designed and built 110 prototypes for all of the different components inside Polyformer.

How it is different

While in Rwanda, we first tried to manufacture filament via plastic shredding; the most popular technique to fabricate filament. We shredded waste plastics into small pieces and then fed the grounded material into a semi-industrial leadscrew extruder (Wellzoom). While this process worked, it wasn’t reliable - the shredded plastic routinely jammed the extruder. We wanted to build a more dependable machine for recycling plastics into filament. The Polyformer has three key features which make it better than any other filament extruder. First, and most importantly, the Polyformer is a finished design that has gone through many iterations and has numerous global users - it is not a prototype still in development. Second, the Polyformer is less likely to jam, since it's fed a continuous/consistent source material instead of irregular shredded pieces. Third, the Polyformer includes a joiner mechanism that allows users to fuse filament segments into longer strands.

Future plans

Our short-term goal is to deploy several Polyformers at 3D printing labs in Rwanda. This will ensure Rwandans have access to affordable filament and means to recycle plastic bottles. After collecting user feedback, we will gradually promote the project in other developing countries. With its low cost of $150, we know that Polyformer is financially accessible to many communities. Excitingly, over1200 users have joined our project Discord in the past two months. Already, many people around the world have built Polyformers. Hopefully, they will form groups around them, inspiring even more people to join the plastic recycling process.


-Documentation available on our Discord: (1200 members+). We commend everyone that contributed to this effort to give waste plastics a second life. In particular, we thank Joshua Taylor who served as a mentor to us. -Spark Awards Spring 2022 Students - Platinum -Hackaday Prize Finalist 2022

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