Meryl Streeps signature look from the 2008 film gets an origin story of its own inMamma Mia!

But actually, in the end, we went for them really pretty similar to Meryls.

But fidelity to the spirit of the character wasnt the only consideration.

It was really important, because theres so much dancing and movement, that they stretch, she says.

We went through so many, and we went through so many different shades.

We were dyeing it, like, weeks, just trying to get the right shade.

Theres also the issue of overalls being, you know, pretty shapeless much of the time.

They either have to fit in every dimension or not fit at all.

Its so many different aspects, I dont think people even realize, Clapton says.

Its like, Its just a pair of dungarees, get over it.

But actually its really complicated to make them do everything they need to do and look good.

All the work paid off when James got into costume.

The garments first appearance, teased in the video, is quite a defining moment, Clapton says.

It says quite a lot about her.

So what does this particular piece of denim communicate about its wearer?

It would have been wrong [to have her] in pretty dresses all the time.

Its part kid and part worker and part fun, Streep sums up the look in the featurette.

Theres nothing that outfit wont do.

My, my, how can we resist it?

Check out the exclusive featurette above.Mamma Mia!

Here We Go Againhits theaters July 20.