If you’re wondering what a retired LEGO mold looks like after producing 120,000,000 bricks, the above image shows it. A recent picture that was posted on Reddit shows a mold that was producing red 2×3 plates in it’s last cycle of it’s life. A commenter did calculations on how long the mold lasted and suggests it’s been at work for around 7 years nonstop, minus maintenance and color changes.
120,000,000 bricks / 8 bricks per cycle = 15,000,000 cycles
15,000,000 cycles / 4 cycles per minute = 3,750,000 minutes
3,750,000 minutes / 60 minutes per hour = 62,500 hours
62,500 hours / 24 hours per day = ~2604 days
2604 days = 7.135 years
According to the Pick-A-Brick page on Shop@Home, these 2×3 plates cost $0.15 each so if prices haven’t changed since the mold started production, it would’ve made LEGO around $18,000,000. As someone who has worked in the plastics industry before, the molds are the centerpiece to getting the bricks produced. Needing to be very intricate and precise, they can cost upwards of tens of thousands of dollars to make. They take a few hours to change out of the plastic injection machines and can weigh between 150-1500 kilos. If you have time, I suggest watching National Geographic’s Ultimate Factories/Megafactories of the LEGO factory in Denmark on how the bricks are created. The video talks more about the molds starting at 13:15.