Sam Carlin likes building things, but nothing he's built has had a greater impact on the lives of others as the treadmills he's created at his Sturgis home for nearly two decades.
"Some place in the house, I've gotten letters from parents saying what a blessing it's been for them," Carlin said.
Carlin created Carlin's Creations, and since 2000 has been building pediatric treadmills. They were first built for researchers at the University of Michigan.
Dale Ulrich was conducting what he calls "basic science." He was hoping to learn if there was a way to help children with Down Syndrome learn to walk earlier than normal.
"The value of walking for any child is critical," Ulrich said. "Once a child can crawl or walk they get to explore their environment, and they'll learn; they get to socialize, they get to communicate more."
Ulrich said babies with Down Syndrome typically learn to walk between the ages of 2 and 3.
"Having a child that's delayed, they're going to likely be delayed in all of those domains as well, and so as soon as they can begin to walk you see a big increase in all of the developmental domains," Ulrich said. "Just because historically these babies were not walking before 2 years or older, that doesn't mean we shouldn't be trying to be creative and figure out ways to reduce that delay."
Through his research, he learned those same infants could start using a treadmill to train their legs, and by the time they were 8 or 9 months old.
Once he learned that, Ulrich and his team reached out to Carlin, asking the Sturgis man to build several treadmills for the infants.
"You can move it like airport luggage," Carlin said as he showed off his creations.
Ulrich was able to work with dozens of infants with Down Syndrome over a span of three years, using the treadmills to train them how to walk. He would visit the homes of the families taking part in the study.
"Soon as I walk into the home, the babies start crying," Ulrich said. "They see me coming in and they know it's time for treadmill training."
Ulrich's work discovered that the treadmills helped the babies learn to walk earlier.
"Sure enough, they begin to step and every month they get better," he said.
Ulrich said on average his research lead to the children learning to walk six months sooner than what's typical for an infant with Down Syndrome.
"For us to know children are still using it and benefiting," Ulrich said, "I'm driven by those kinds of emotions."
While that study wrapped up nearly 15 years ago, Ulrich said the treadmills are still being used today.
"A lot of clinics - physical therapy or medical clinics - are purchasing them, some of which rent them then to parents," he said.
Carlin said he's made almost 400 pediatric treadmills since 200 and is still shipping them globally, all from his home in a quiet neighborhood in Sturgis.
"Australia, Canada, the UK, Israel," he said of the countries where his treadmills can be found.
For Carlin, the letters and pictures he's received are filled with smiles and stories of lives improved and that lets him know he's made a difference.
"It's been wonderful," he said. "It's nice to get those."