Newswise — Hailey Dawson throws a powerful fastball. Armed with her UNLV-built "Robohand," the Henderson 7-year-old has already delivered the opening pitch for the Baltimore Orioles and the Washington Nationals, and has invites to pitch by all other Major League Baseball teams.

Now, she’s preparing to throw out the first pitch Oct. 28, at the fourth game of this year’s World Series.

Due to a rare condition called Poland Syndrome, Hailey was born without a right pectoral muscle; her right hand is missing three fingers and her thumb and pinky also are undeveloped.

Three years ago, Hailey's mom collaborated with UNLV College of Engineering students and faculty to design and build a 3D-printed prosthetic hand. 

Each robohand takes at least a week to make. The process requires a mix of biology and kinesiology know-how (to understand how the human body and muscles involved in various grasping motions work), along with math (to calculate part dimensions and build 3D models) and engineering (to design components that are small yet thick enough to not break).

The hand uses no electronics. Rather, when Hailey flexes her wrist, the fingers move in or out of a grasping shape.

Hailey started three years ago at 60 percent of a full-sized (100 percent) model, and is now at 83 percent. Hailey likely will need a new hand each year as she grows. 

The current model, designed by engineering graduate student Maria Gerardi, can be adjusted to fit anyone without a fully-formed hand by taking a photo of the wearer’s hand, calculating measurements, and digitizing them through the computer software.

For now, the hand is for general use (holding bags, occasional writing, etc.) and Hailey hasn’t been picky about design — usually they are hand painted with a theme such patriotic colors or as a team logo for opening pitches. 

But UNLV student and faculty engineers continue researching ways to improve the design in case Hailey wants hands for specific purposes, such as writing or other tasks/sports as she gets older.

Learn more about Hailey's journey at