While we know Cruella de Vil has a sense of style from the previous works, Gillespie created a style explosion in his film.
"It just kept evolving," he said. "It just kept getting bigger and bigger as we were working with the character and she becomes this fashion maverick, we had to create these set pieces worthy of that. And being set in that punk world, and having that attitude - mopeds turning up at events and garbage trucks driving into red carpet events - it was really fun to work with."
EXCLUSIVE: Emma Stone talks 'hilarious, wild' 'Cruella' origin story
It's a movie that needs to be seen on a big screen.
"I wanted to make a film that would be an enormous amount of fun to go watch, just to have a blast. Obviously, there's the gravity and a real emotional journey, but I just wanted to walk out of there smiling," said Gillespie.
Dog lovers may fall in love with the film and its canine stars. But they weren't necessarily the easiest actors on set.
"I gotta tell you, Dalmatians are not that easy to work with, particularly when there's always three of them at once," he said.
The project also gave him the chance to learn some new things about a character as iconic as Cruella.
"She's gotta stay true to herself," Gillespie said. "She's got a society which is trying to suppress her, color within the lines in the 60s, and she's being punished for it and not being true to who she is. It's not until she truly leans into who she is and her true nature, that's when she blossoms."