The world’s best athletes will receive their gold medals at the Paris Olympic and Paralympic Games this summer while standing on trash. Recycled food containers, to be exact.

The silver-colored Olympic podiums, currently being raised across France, were made in a small factory on the outskirts of Paris by a start-up called Le Pavé using 100 percent recycled plastic. It’s a first for any Olympic Games.

“There is an overabundance of plastic that is harming the environment, but which also has proven economic potential if it can be repurposed,” said Marius Hamelot, 29, a co-founder of Le Pavé, as he darted around his plant, a converted former steel foundry.

That’s not all: Le Pavé also made 11,000 bleacher seats for two nearby sports arenas that were built for the Games — all manufactured from used shampoo bottles and millions of multicolored bottle caps.

Just a few years ago, the company had only three employees. But an unexpected call from Olympic organizers led to a beefy contract, and the company has expanded to a staff of 34 and opened two factories. In the process, it has become a poster child for the Paris Olympic committee, which has pledged to make these Olympic Games the greenest in history.

Le Pavé is part of an increasingly dynamic start-up culture that has been growing in France, seeded by ambitious policies from President Emmanuel Macron’s government to transform the economy with new industries focusing on clean technology and a green transition.

“It used to be considered a start-up if you just developed software,” said Jim Pasquet, 31, Le Pavé’s other co-founder. “We are a new type of industrial start-up, focused on environmental needs, and our goal is to become a European leader.”

Mr. Hamelot had already been working to convert plastic waste collected in Parisian neighborhoods into high-quality components for the building sector. As an architecture student at the University of Versailles, he had set his sights on the construction industry, one of the biggest sources of carbon emissions.

“The two things common in construction are waste and trash, everywhere in the world,” he said. “How do you reinvent the materials used to build and that won’t harm the environment?”

Mr. Hamelot bought a used pizza oven and began to experiment with melting discarded plastic from electronic detritus, including old coffee makers and telephone handsets that he chopped up in a blender. In 2018, he and Mr. Pasquet, friends since childhood, created Le Pavé and won a series of innovation competitions that got them into La Ruche, an incubator in Paris with a focus on social entrepreneurship, digital technology and crafts and culture, where they raised modest funding.

By 2019, they had patented a thermal compression molding technology for use in the building sector. Soon after, Mr. Hamelot got a call from Solideo, the French company overseeing infrastructure for the 2024 Games, including a new Olympic Village in the northern suburbs of Seine-Saint-Denis that was designed to promote zero waste.

The organizers, who were seeking to slash planet-warming emissions in half compared with previous Games, asked if they would be able to produce 11,000 chairs for a new Olympic Aquatic Center being built to host swimming, and for the new Adidas Arena, which would hold gymnastics and badminton competitions.

“It was an incredible opportunity,” Mr. Pasquet said.

Seeded with money from BPI, a French state investment bank that focuses on start-ups, they settled into an abandoned steel factory in Aubervilliers, a low-income suburb of Paris near many Olympic venues.

Mr. Hamelot and Mr. Pasquet worked with 50 local recycling companies to gather used plastic, experimenting with dozens of prototypes and stress testing before inking a final deal with Solideo in 2022 for the stadium chairs.

Armed with a philosophy that asserts working locally can have a big social impact, they hired employees from Seine-Saint-Denis, including people who had been on long-term unemployment, as well as an asylum seeker and a former prisoner eager for a fresh start.

The company added an educational dimension, asking a nongovernmental organization, Lemon Tree, to include 50 elementary and middle schools in the Ile-de-France region. Around 1,700 schoolchildren collected one million yellow bottle caps that were used to infuse the black-and-white stadium chairs with flecks of color.

As they learned about recycling, the children peppered Mr. Hamelot with tough questions about the environmental impact of plastics and how to reduce carbon emissions. “The kids were critical and seriously involved,” he said.

All told, Le Pavé used 100 metric tons of recycled bottles and bottle caps to make panels for the 11,000 stadium seats, which were pressed into form by a French company specializing in arena seating. To create the panels used for the 68 silver-hued Olympic victory podiums, Le Pavé used 18 metric tons of recycled plastic and plastic foam food containers.

On a recent day, eight people bustled around the factory in Aubervilliers, where a rainbow of recycled plastic beads and chips stood in huge sacks. Some workers used a forklift to feed beads into a special heater, while others guided the finished panels through a cutting machine.

The recycling process itself does leave a carbon footprint, including from heating the ovens and cutting the plastic panels. Even so, Mr. Pasquet said, it emits much less carbon dioxide than using virgin plastic does.

“We’re making something beautiful out of old trash that is cluttering the planet,” he said.

They are opening a second small factory in the Burgundy region of eastern France, and are raising funding to open two more in the west and in the south. As the government seeks to reindustrialize France, Le Pavé’s aim is to create jobs by opening small factories, Mr. Pasquet said, adding that the old model of mega factories no longer met today’s environmental and social challenges.

Le Pavé’s Aubervilliers factory served as an exclamation point to that statement: All the major equipment was painted bright pink instead of industrial gray. “We want these to be the new colors of industry, to get away from the old image,” he said.

Recently, the Élysée Palace, the official residence of the president, installed a decorative wall made by Le Pavé. The company is also producing panels for major French furniture retailers and has projects in the pipeline to make parquet-style flooring for homes and buildings.

Knowing that their ideas have come to life for the Olympic Games has been a huge motivator. “We see that we have an opportunity to build something that will last for years and years,” Mr. Hamelot said. “This is about something that’s bigger than all of us.”