MANKATO — Todd Bain doesn’t play guitar, but he cradles the strumbly like it’s an old friend he’s been strumming on for years.

Maybe that’s because he helped create it. From the wood frame to the strings, Bain and other classmates in his physics class at Bethany Lutheran College designed and built the “poor man’s guitar,” as Bain calls it, as part of a class project.

Not just the strumbly, either. Five teams of students in College Physics and General Physics classes created the strumbly, an electric guitar, a double reed, a hammered dulcimer and a bowed psaltery, all of which will be played by professional musicians at a presentation Monday night at Bethany — because most of the students can’t play a tune.

And that’s OK. This project, dreamed up by the students’ professor Peter Kjeer, isn’t about musical appreciation. It’s about appreciating what goes into creating that music — the physics behind the instruments.

The frequency of the notes, the tension and length of the strings, the distance between the frets and the exact placement of every component must be considered and calculated when building an instrument. Most people probably don’t realize how much science is behind the music they hear every day, Kjeer said.

“It’s good, hands-on experience for learning how music is made — dissecting the instrument inside and out,” Kjeer said.

These aren’t meant to be makeshift folk instruments, either, which allow for grittier, less formal sound qualities. They’re meant to be functional, precise, playable instruments up to the sound standards of those purchased at a store.

That’s an incredible challenge, said Adrian Lo, professor of music who will play the hammered dulcimer during Monday night’s concert. But from what he’s observed, the students have done an incredible job.

“(The hammered dulcimer) is beautifully built,” Lo said. “You can go to a music shop and buy one, and it’ll be very close to this quality. This particular one is amazing.”

Lo has been a string player for many years. To help get a better idea of the precision of design and physics behind an instrument, there’s no better family than strings to examine, especially the violin.

Correct spacing of the strings is vital. The position of the soundpost is critical to the sound quality. Even a tiny fraction of a millimeter off will create a noticeable difference.

The condition of the hair on the bow will affect the sound. Worn strings will break or fray. Humidity affects the functionality of the rosin.

“It’s all physics, craftsmanship, engineering (and) empirical experimenting,” Lo said.

And that’s precisely what Kjeer hopes his students have learned this semester and what he hopes they will be able to teach the audience. Students and professors will act out a skit to provide an audience-friendly and funny look at how harmoniously science and music go together.

“It’s not just ‘Fold Flap A into Slot B’ and you’re done,” Kjeer said.

Nick Ollrich and Ryan Campion, who built the electric guitar, know that now.

“We didn’t think it would be as hard as it actually was,” Campion said. “It makes you a lot more aware of what you’re seeing.

The instruments will go in a glass display case in Meyer Hall at Bethany after the performance and will be used next year as visual aids in the classroom.

Kjeer introduced the project last year and students designed and built various instruments, including a harp and an electric guitar. He plans to carry on the annual project and presentation next spring.