Derby was never very good at fetch. He was born with a disability and it seemed like a cart with wheels was his best option — until Tara Anderson built him a brand-new pair of legs.

“I kept looking at his photo and reading his story, and I cried literally every time,” Anderson, an employee of 3D Systems in Rock Hill, South Carolina, said in a viral video that has now been seen more than 2.27 million times. “I had to try to help this dog.”

At first they tried a cart with wheels, but that limited Derby’s mobility, especially when playing with other dogs.

Watch what happens when Derby gets his own pair of prosthetic legs thanks to 3D printing. 

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