- [Narrator] Every invention starts with an idea.

- We're trying to see how much play there is.

- [Narrator] For Tahira Reid Smith, her idea comes from a childhood passion, Double Dutch.

- [Child] One, two, three, four, five, six, seven, eight, nine, 10, 11, 12, 13, 14... - Growing up in Bronx, New York, in the 1980s, Double Dutch was just what you did as a little girl.

- [Narrator] This double-rope version of jump rope was brought to New York by Dutch settlers in the 17th century.

More recently, it became popular, particularly, among Black girls in cities across the US.

To play, Double Dutch requires two people spinning ropes in opposite directions, and at least one person to jump.

(intriguing upbeat music) Tahira dreamed of a machine that would allow her, an only child at the time, to play Double Dutch whenever she wanted.

In third grade, she won a contest for that concept, and in the years that followed, she never gave up on that dream.

- Major passion project.

Talking about an idea that I've had for decades.

- [Narrator] Today, she's a mechanical engineer and professor working in human-machine systems, and she's building to her ultimate dream, to create an affordable version of her invention that people everywhere could enjoy.

Meanwhile, after decades, Tahira is finally taking her own Double Dutch design to the next level.

(intriguing upbeat music) - And when we've done small tests... - [Narrator] She's partnering with a product design company to turn her prototype into an affordable, consumer-ready version.

- Historically, what has been difficult has been how to design this system in such a way that it's fully functional and also cost effective.

- [Narrator] Which is why she still thinks that the most practical approach is to use only mechanical means to synchronize the motors.

Tahira and director of industrial design, Steve Escobar, are deep in the proof of concept stage.

For now, they're working with a rudimentary plywood model, to answer a few basic design questions.

- Once you have an idea, how are you gonna actually execute the idea?

How are you gonna design the idea, so that people will actually wanna use it?

How are you going to make it accessible both from a cost perspective, but also from a user interface perspective?

- [Narrator] This first iteration of the design uses just one motor on each side, plus, some good old-fashioned mechanical hardware, like gears, sprockets, and chains.

Already, they're facing a few familiar challenges... - Looks like it's in sync, actually.

- [Narrator] Including, getting the ropes in sync.

- [Tahira] It's starting to go out of sync.

Okay.

- [Narrator] With years of Double Dutch experience, Tahira knows exactly what the ropes should sound like.

- We need to be able to hear a consistent pat, pat, pat, pat, but we're hearing... (Tahira imitates ropes thwacking asynchronously) - It's very rhythmic.

That's why, when stuff's out of beat, it's like the whole...

This is just wrong.

- If anything slips, it would be a tooth... - [Narrator] Using gears is a common sense way to keep the rotation of the ropes in sync, but something is wrong.

- We think the weight of the rope is throwing this off.

- When it's in motion, it's actually creating too much force for these arms.

- Let's take some of these off and let's see what happens.

Let's see.

Let me just listen for it.

(ropes thwacking rhythmically) - [Michael] So how's it going?

- Yeah, it's coming along.

- [Narrator] Michael Sprauve, President of Speck Design, stops in to see how things are progressing.

- Where are we at, guys?

- [Narrator] As a team, they talk about the day's testing and how to improve the design.

- There's a lot to think about with some of the play that's still in the arms.

- It's extremely important to have different people who can see things from a different angle, 'cause each one of us have our own blind spots.

- The best moments of ideation are, in my experience, collaborative, and they involve ideas bouncing off one another, being folded over.

The negative of that idea being turned in into the positive of this other idea.

- [Narrator] Though a lot more troubleshooting remains, Tahira's project is finally coming to life after decades of work.

- Semi-surreal, exciting.

It's a lot.

It's heartwarming, it's... (Tahira sobbing) I'm just glad.

There's a message behind this product.

When it gets on the market, there's a story to inspire young girls, young inventors, young minds, dreamers.