The majority of the handwork is done away from the roaring machines behind the soundproof walls of Grove's "quiet room." They sand bamboo while listening to music or audiobooks, such as "The Hunger Games."
"A person has to decide how much to sand," said Tomita. "You have to be paying attention. The quality really depends on how much people care."
Companies making cases for Apple's products are left in the dark until the last second.
