His family members said they are perpetually in awe of how Lucas manages without one of his hands. But they were disheartened when he would complain that his classmates would ask him about it, and Lucas would occasionally ask when his palm would grow into a real hand.
"I wanted to see what he could do with two hands," Gabriel said.
O'Connor said he was privately skeptical about being able to build a hand for Lucas. O'Connor is a hobby carpenter but was a novice on the 3D printer and had mostly assigned students to build small puzzles, key chains and fins for model rockets, all far less sophisticated than a prosthetic hand.
But he welcomed the challenge and was moved by Gabriel's dedication to his little brother.
Gabriel helped O'Connor identify a blueprint and worked to scale the model to his brother's proportions.
O'Connor spent about 40 hours constructing the hand, meticulously printing out pieces and assembling them; the machine put in about 30 hours of printing as it fabricated the hand's parts. O'Connor had to scrap two partial models that were too big for Lucas, but he plans to save them so he can build Lucas additional hands as he grows.
Maker Smith, a group that provides space and equipment for high-tech tinkerers and inventors, also helped O'Connor with the project, donating an expensive, flexible material that forms the joints of the fingers.
On Lucas's sixth birthday two weeks ago, his mother, Romina Barrera surprised him with a trip to O'Connor's classroom, where he was fitted with the hand for the first time. He reached for his mother's cellphone, then grasped cups and small boxes before taking a tour of the high school and giving high fives.
It was an emotional culmination of a long journey.
"I don't know if I've ever been able to see that type of excitement or to experience something like that," O'Connor said. "It was pretty cool."
The hand attaches to Lucas' arm with Velcro. By bending his wrist, he can manipulate the fingers to pick things up. On his birthday, he began by picking up small boxes. He is slowly developing the muscles he'll need to build dexterity, moving on to glasses of milk and stacks of paper.
O'Connor said he hopes to have his students work on prosthetic hands for Enabling the Future so that he can teach them engineering while also helping out other children like Lucas. It is precisely the kind of teaching the school district encourages, having students learn through projects while tackling real-world problems directly.
Lucas said the real-world problem he'd like to conquer is the one task that sets him apart from his classmates at Sterling Elementary: tying his shoelaces.