With Nebraska Repertory Theatre’s production of “Big Fish,” and its cast of magical creatures, Hunter Rock has faced the biggest challenge of his creative career.

A master’s student, Rock has created costumes for numerous productions across his academic career. None, so far, have included giants, witches, mermaids or werewolves — that is, until he learned of Nebraska Repertory Threatre’s production of “Big Fish,” now showing through May 4.

“Logistically, this is probably the most challenging show I’ve ever worked on,” Rock said. “The show jumps around between multiple time periods with numerous costume changes. It’s a bit daunting because you have to keep a cohesive look to everything across the show — it’s a lot like a puzzle.”

The show, a fantastical musical that time-hops through imaginary worlds, includes a larger cast than Rock had previously managed.

“You have to start with what the absolute needs are — things already in the script or what the director wants to see in the designs — and then work from there,” he said. “If the script specifies a color, I can use that to help build a color palette for the character that runs across the show. Then you can work with that to build a larger idea.”

The magical aspects of the show allow Rock’s imagination to run wild, especially when it comes to designing the creatures of “Big Fish.”

“A lot of designing the creatures comes down to working with our actors,” he said. “For things like werewolves, we’ll do things to make their faces seem pointier like a dog’s. For giants, we’ll use stripes to help elongate their form. I like to make it feel grounded in reality and not something cartoonish.”

Without disclosing too much about the show, Rock teased that there are certain human-to-creature transformations directly on stage that he’s particularly proud of helping realize.

“I don’t want to give too much about the show away, but there’s a moment where a character dances across the stage and, in the process, transforms in a way that’s really exciting and unexpected,” he said. “That’s been a fun challenge to figure out, and I hope that moment sticks with people as something they’ve never seen before.”