Design Problem

In Kenya and many other parts of the world, plastic waste—especially PET bottles—poses a serious environmental challenge. At the same time, 3D printing is becoming more accessible and widely used in education and prototyping. However, the cost of importing filament can be prohibitive for local schools and makerspaces. This project aims to solve two problems at once: reducing plastic waste and creating affordable access to 3D printing materials. By building a low-cost machine that converts discarded PET bottles into usable filament, we can empower students to recycle plastic locally while also supporting innovation and hands-on learning in schools. There is a clear need for a sustainable, scalable solution that is simple enough to be replicated and repaired in local contexts.

Design Process

The design process began with research into existing open-source filament maker projects. After reviewing several designs online, I selected a basic schematic that uses a heated nozzle to extrude plastic strips from PET bottles into 3D printer filament. I adapted this design to make it as affordable and locally replicable as possible, sourcing parts from local hardware stores and reusing electronic components where possible.

The main stages of the build included:

• Prototyping the bottle-cutting mechanism to create uniform PET strips.
• Designing and assembling a heating element and nozzle to melt and extrude the PET.
• Adding a motorized feeding system to pull the filament through consistently.
• Testing different temperatures and feed speeds to achieve stable filament thickness.

One of the biggest challenges was maintaining a consistent diameter of filament. I overcame this by adjusting the feed motor speed and experimenting with cooling techniques after extrusion. Another issue was power regulation for the heating element, which I solved by integrating a simple thermostat and insulating the barrel to reduce heat loss.

Here is a photo of the machine during early testing:

This project is still evolving, but the current prototype successfully produces filament suitable for basic 3D printing applications. Future iterations will aim to improve filament consistency and build a filament winder for better spool management.

Link to Process Journal and Final Reflection Video

https://sites.google.com/isk.ac.ke/pet-plastic-bottle-3d/home