The Kenyan entrepreneur behind Gjenge Makers has built a business around a practical question: how can discarded plastic become something useful?
Plastic waste is often discussed as something to collect, remove or throw away. Nzambi Matee approached it as a material worth investigating.
The Kenyan entrepreneur founded Gjenge Makers in Nairobi to turn selected plastic waste into construction products. Her work connects engineering with a familiar urban challenge: finding a productive use for materials that might otherwise be discarded. In 2025, she was recognised among The Explorers Club 50, which highlights people whose work advances exploration and positive change.
Her journey offers a useful perspective on entrepreneurship. Identifying a problem is a beginning; developing a dependable product requires experimentation, equipment and people willing to keep working through uncertainty.
Starting in a Backyard
According to the United Nations Environment Programme, Matee left her job as a data analyst in 2017 and began experimenting in her mother’s backyard. She tested combinations of plastic and sand, investing her savings in the project. The machinery was noisy enough to attract complaints from neighbours.
An opportunity to attend a social entrepreneurship programme in the United States later gave her access to laboratories at the University of Colorado Boulder, where she refined her material mixtures. In December 2020, UNEP named her a Young Champion of the Earth.
Those early stages are worth remembering when looking at the finished product. A colourful paving block can appear straightforward. Developing a repeatable way to manufacture it is a different task.
Building the Machines, Too
Matee’s challenge extended beyond finding the right material.
Impacc, which lists Gjenge Makers in its investment portfolio, recounts how she obtained a functioning hydraulic arm from an old excavator in a scrapyard and used it to build her first hydraulic press.
The organisation describes a production process in which waste plastic is shredded, combined with sand and pressed into construction products. It also identifies opportunities for women, young people and waste collectors within the business’s activities.
The machinery is an important part of the story. An experimental sample demonstrates an idea; production equipment makes it possible to manufacture that idea repeatedly. Matee had to work on both.
How Plastic Becomes a Paving Product
Reuters reported in February 2021 that Gjenge Makers used selected plastics, including high-density polyethylene, low-density polyethylene and polypropylene. At that time, Matee said the factory did not use PET, the plastic commonly associated with drinks bottles.
The report described plastic being mixed with sand, heated and compressed. It recorded production of approximately 1,500 blocks a day - a historical figure, rather than a verified measure of the company’s output today.
That distinction between plastic types matters. Recycling involves understanding the properties of the material being processed. “Plastic waste” covers different substances, and a manufacturing method developed for one mixture should not automatically be assumed to work for every discarded plastic item.
The same care applies to construction claims. A paving product should be assessed for its intended use. Its performance does not, by itself, establish that it can replace every conventional building material.
A Business With a Wider Purpose
In her contribution to The Explorers Club’s 2025 profile, Matee linked her motivation to plastic pollution she had witnessed in Nairobi and along Kenya’s coast. She also described employment opportunities for women and young people as an important reason for continuing the work.
This gives the business a broader context. Recovering material can involve collectors, suppliers, machine operators and customers. A useful product creates a reason for those relationships to exist.
That is the practical appeal of a circular economy: keeping materials in use through products that people have a reason to buy. Its success depends on the details - reliable supply, consistent quality, suitable applications and a workable business model.
What Her Journey Can Teach Us
There are three useful lessons to draw from Matee’s experience.
Begin with a specific problem. A clearly defined challenge gives an idea direction and makes it easier to judge whether a proposed solution is useful.
Treat experimentation as part of the work. Testing and revision help turn an interesting concept into something dependable.
Pay attention to production. For a physical product, the ability to make it consistently can be as important as the original invention.
What problem in your community deserves a closer look? Share your thoughts in the comments.
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