This amazing Taiwanese man built himself an artificial hand from scratch (Video)
After many attempts, Chang said he produced an arm with moveable fingers that cost about $4,000.
"I was very happy and excited, finally my design could be used," he said.
Now, Chang wants to help others.
He is designing and building a prosthetic hand for Angel Peng, an 8-year-old girl whose hand was crippled in a scalding accident when she was nine months old. Her mother Peng Ji-han said they heard about Chang at Angel's clinic.
"She grew up thinking it is normal not to have one hand," Peng said, adding she could not afford an expensive prosthetic for her daughter.
Angel's eyes widened excitedly as she tried to use an early product of Chang's 3D printing to pick up a bottle.
She said she could hardly wait to use her new hand.
"When my hand is done, I will hop onto a bike immediately," she said.