"We love using the carrier with Bosley because we designed the print with him in mind," Horn tells PEOPLE

Life has come full circle for The Guncles.

Bill Horn and Scout Masterson, the reality couple and best friends of Tori Spelling, are now settled in as parents to two children, 1-year-old son Bosley Jo and 5-year-old daughter Simone Lynn, whom they welcomed with the help of the Independent Adoption Center.

Now the dads are giving back to the agency that worked with them to become a family of four by teaming up with LÍLLÉbaby to create a custom baby carrier. A portion of the proceeds will be donated to the organization.

“We knew we wanted to design a bold, geometric print that was cheerful, sophisticated, and unique,” Horn and Masterson say. “We are proud to be able to use this project to benefit a charity near-and-dear to our hearts.”

The colorful pattern (designed by Masterson using a box of crayons!) is available on the brand’s Complete All Seasons Baby Carrier ($160) as well as their mini doll carrier ($40).

And the dads’ limited edition version already has a huge fan base: Celebs including Tiffani Thiessen, Emily Maynard, Marla Sokoloff and Sherri Saum took to social media Tuesday to share their excitement.

In honor of the launch, Horn chatted with PEOPLE about the inspiration behind the bold print, the children’s recent milestones and Simone’s purple hair!

Bill Horn Scout Masterson Guncles baby carrier

Courtesy LILLEbaby

PEOPLE: Congratulations on your collaboration! What made you want to design your own carrier?

Bill: LÍLLÉbaby has always had such a wide variety of unique and fun prints, so we were excited when they suggested we collaborate. And we love using the carrier with Bosley because we designed the print with him in mind.

PEOPLE: Can you explain a little bit about the design and colors? Any meaning behind the pattern?

Bill: We knew right away that we wanted to design something bold with geometric shapes. As soon as LÍLLÉbaby brought up a collaboration, Scout bought his own set of crayons and a new ruler. Then he spent the afternoon sketching the picture that would ultimately become the print on the fabric.

It’s very rewarding to see the design come to life in fabric — and it was a lot of fun! We are thrilled that we can help give back to the IAC, the agency that helped us find our babies.

PEOPLE: Other than freeing up your hands, how has a baby carrier helped in your relationship with your kids?

Bill: We use our carrier all the time. It’s much easier to navigate the grocery store, amusement park, or farmers’ market with Bosley in the carrier while Simone holds our hand. Plus, it’s a great way (for all parents) to bond with their child.

Bill Horn Scout Masterson Guncles baby carrier

Courtesy LILLEbaby

PEOPLE: What are Simone and Bosley up to these days? Any recent big milestones?

Bill: Bosley just turned 1 and we can’t believe how quickly the year went. He’s days away from walking and we couldn’t be more petrified! Baby boys are a force of nature. We were not prepared! He’s into everything.

Simone started kindergarten a few weeks ago and LOVES it. We drop her off and she runs for her classroom.

PEOPLE: Speaking of Simone, we’re loving the purple streaks in her hair! Was she feeling inspired?

Bill: We can thank Disney’s The Descendants for the purple hair. The moment Simone spotted the first commercial (even before the movie aired), she saw the character Mal had purple hair.

We (obviously) weren’t allowing our 5-year-old to get her hair dyed bright purple — BUT we did compromise with tape-in, temporary extensions. She LOVES her purple hair!!

PEOPLE: Bosley recently turned 1 — how did you celebrate?

Bill: For Boz’s first birthday, we kept it very low key: invited over a few friends and family, swam and ate cake. The past year, 2014-2015, has been rough for our family (we’ll explain why one day), so we just wanted to keep it small.

PEOPLE: What’s the relationship like between Simone and Bosley? Any cute stories?

Bill: Simone and Bosley have a bond that amazes us daily. He worships her and wants to do and touch everything she does in the house. When she’s around, he wants 100 percent of her attention.

She loves to pick him up, kiss him, and scream, “I love you, my little Moochi!” (Not sure where she got that nickname — maybe because she loves putting mochi on her frozen yogurt.)

If we had any fears a year ago about them not bonding, those have certainly vanished. Their genuine affection for each other makes us realize all the hard work it took to become parents was well worth it.

— Anya Leon