At Valley Crossing Elementary in Woodbury, Everett Kroll was a squirrely kid with undiagnosed ADHD — he was the one who blurted out while his teacher talked and had to make frequent visits to counselors and the principal’s office.

But when Everett transitioned to Oak-Land Junior High, something switched: all that roaming energy was channeled into one subject. He spent his free time building things out of Legos. His mom said he became “passionately curious” about how things worked after taking an engineering class through Project Lead the Way.

The spring of his ninth-grade year at Stillwater Area High School, a month after making it to the Minnesota state science fair for building a tank out of Legos, Everett told his mother he wanted to build a prosthetic leg. She told him to slow down, that he’d only just finished his latest project.

Everett did the opposite. His sophomore year of high school, he ate lunch in the library every day to read more than 5,000 pages’ worth of research. That year, he advanced to the international science fair in Los Angeles for the leg, created by 3-D printing.

This year, as a junior, he was seeing stars in front of 1,800 young scientists when he heard the judges call out his name: “First place in biomedical engineering goes to Everett Kroll.”

Everett’s win came at the Intel International Science and Engineering Fair in Pittsburgh on May 17 for his creation of a prosthetic foot — affordable and durable and created by 3-D printing. The fair, which is the largest international high school science competition, involved 1,800 students from more than 75 countries. Everett was awarded $3,000 in prize money.

“We had no idea he’d turn out so focused,” said Christine Kroll, Everett’s mother.

Everett works at DSW and as a softball umpire. He’s also the captain of his robotics team and participates in Science Olympiad, the Science Bowl, physics club and cross country. Oh, and his junior year, he took four classes for college credit.

One time, he brought a piece of plastic to his cross country practice and asked his teammates to run, jump and step on it. He wanted to see if the material would be durable enough to be molded into a foot.

He’d often stay up until 2 a.m. trying to learn an equation for his project before realizing he needed to study for a test the next day. Everett said those nights — when he was overwhelmed and crying at his desk — flashed through his mind as he walked up to receive his award.

“I was thinking about all the times I failed,” Everett said. “But science helps you recognize that bad things are good things.”

His first prototype was made on the high school’s 3-D printer. When Everett stepped on the prototype to test its strength, it snapped and cut his foot open.

He made 53 more prototypes before he came up with the prosthetic that would win him the international prize. It was printed at 3M Co. after a neighbor connected him with a 3M employee. Related Articles Washington County: Funeral services set for drivers who died in last week’s head-on collision

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Everett said a 3-D-printed prosthetic foot for a 300-pound person would cost around $20 to make, depending on the person’s level of mobility. His goal would be to sell the product at as low a price as possible, so that anyone whose foot has been amputated could afford a quality prosthetic.

He’d like to eventually strike a deal with an organization like Fairview, 3M or Doctors Without Borders.

Everett wants to earn his Ph.D. in either biomedical engineering or mechanical/applied physics and mathematics. He is still unsure of where he wants to go for college, but says he’s looking at the top 15 engineering schools in the country.