It was originally a long-sleeve dress with a mock turtleneck. I wanted to change it up, though ... Not only does Barbie have a Dreamhouse on set, but she loves to stage all kinds of scenes ...

"Margot and I marathoned through 50 or 60 outfits," Mukamal told PEOPLE at an event celebrating the release of their collaborative book 'Barbie ... dresses before they set out on their world ...