From cutting plastic from packaging to using plant-based materials, famous toymaker LEGO has been hard at work in recent years to make its beloved toy bricks more sustainable. With that same goal in mind, the company has recently created its first prototype building blocks using recycled PET plastic from discarded bottles.

The new prototype is the first brick made from a recycled material to meet the company’s strict quality and safety standards, and it is the work of more than 150 people who are keeping busy to find sustainable solutions for LEGO products.

Throughout the last three years, the company’s researchers have tested over 250 variations of PET materials and hundreds of other plastic formulations. As reported by designboom, though the prototype meets several of the company’s quality, safety, and play requirements, more testing is needed before the bricks made from recycled plastic will appear in LEGO’s product boxes.

Further tests will involve developing the PET formulation and assessing whether to move to the pilot production phase, which is expected to take about a year. The prototype is made from discarded plastic bottles acquired from suppliers in the US. A one-liter plastic bottle provides enough raw material for around ten 2 x 4 LEGO bricks.

“We are super excited about this breakthrough,” said Tim Brooks, LEGO’s Vice President of Environmental Responsibility. “The biggest challenge on our sustainability journey is rethinking and innovating new materials that are as durable, strong, and high quality as our existing bricks — and fit with LEGO elements made over the past 60 years. With this prototype, we’re able to showcase the progress we’re making.”