LAS VEGAS >> The little girl squirmed in her mother’s arms inside a lab at UNLV, her American flag-themed dress contrasting with the hammers, rulers and other engineering equipment that surrounded her.

After three months of work, the moment had arrived to see how her new prosthetic hand produced on the university’s 3-D printer would fit. UNLV senior Zachary Cook placed the brace that will help her control the hand over her tiny forearm. Once the strap was tightened, the other student, Katy Lau, attached the beige plastic hand over Hailey Dawson’s underdeveloped one.

Hailey’s right hand contains only a thumb and pinky, forming a permanent a “hang-loose” sign, the result of a birth defect called Poland Syndrome. She calls it her “special hand.”

“This is your (new) hand Hailey,” Lau said, fitting the prosthetic on her.

The first draft is close, but it isn’t a perfect fit. The fingers are centimeters too long and the palm is too narrow. Still, it’s a start. The students mark the measurements with a marker and prepare for the second draft.

Throughout the summer, Lau, Cook, Advanced Technical Academies High School senior Kareem Trabia and two UNLV professors have made it their mission to make Hailey a new hand so she can play baseball and ride her bike.

“(The project) is great for our mechanical engineering students,” said Brendan O’Toole, director of UNLV’s mechanical engineering program. “They need to be learning about 3-D printing and honing their computer and design skills.”

The project started with an email to the university’s Howard R. Hughes College of Engineering from Hailey’s mother, Yong Dawson, nearly six months ago.

Dawson had discovered the designs for the plastic hand in an article posted on Facebook. The story described free schematics for an affordable prosthetic hand that could be made on a 3-D printer.

The idea excited her. While Dawson and her husband have raised Hailey to be confident and proud of her “special hand,” it still limits her. She wants to be able to play baseball like her older brother and ride her bike, but with only one hand, it can be dangerous.

“She’s fearless and doesn’t understand she needs more control,” Dawson said. “For me it’s a safety issue, but I want her to do everything else everyone can do.”

After two businesses failed to make a working 3-D printed hand for Hailey, Dawson pitched the idea to UNLV. O’Toole and mechanical engineering professor Mohamed Trabia saw the email in April. After a Google search for the “Robohand” design Dawson described, O’Toole realized UNLV could help.

O’Toole and Trabia put together a team of three students — Lau, a Las Vegas native and Rutgers University student looking for a summer research project, Cook and Trabia.

“My intended interest will be with tissues,” said Lau, a biomedical major. “But who doesn’t want to help a little 4-year-old get a hand and make something that’s going to help the world?”

The students have spent hours in the lab designing the hand for Hailey. It needed to bend forward and backward to hold a handlebar and catch a ball, but they also want to include acrylic nails so she can paint them her favorite colors — pink and purple.

Next, they created a mold of her hands, and then spent hours designing and scaling the prosthetic to her size using a laptop program before sending the schematics to the 3D printer. The printer, which is roughly the size of a vending machine, then created about 40 pieces of plastic fingers, joints, and palm by extruding fine layers of melted plastic that hardens to make the parts. The parts then snap-fit together. The hand will cost $200 to $2,000, depending on how many times the engineers have to print new versions.

Dawson said Hailey isn’t too concerned with the hand. Everywhere the family goes, she shows off her hand to other kids who ask about it.

But she’s also starting preschool at Lamping Elementary School and wants to play ball. Even if she doesn’t use it often, Dawson wants to give her daughter the option of a hand.

O’Toole said the goal is to complete a basic model of the hand this summer and then have senior design students create more and more complex hands for her. Eventually, Hailey’s “special hand” project could help others just like her.

“Students can come up with anything,” Dawson said. “If it can help anybody else, that would just be amazing.”