Ruth E. Carter, who designed costumes for Marvel's "Black Panther," made a one-of-a-kind, mermaid Halloween costume that is worth $25,000. Brittany Reid, 30, who works in communications at a healthcare company in Atlanta, Georgia, won the costume as part of a contest with SpikedSeltzer, a natural hard seltzer brand. "I first had to figure out how the ... costume would move since mermaids swim and don't walk," Carter tells CNBC Make It. That's because the most memorable costumes are "the ones that go into detail of the imagination," says Carter.

The mermaid costume made by Ruth E. Carter at a production partner's studio. Photo: SpikedSeltzer "I envisioned the mermaid in the sea. What would she encounter?" explains Carter. "I thought this mermaid would have great wealth because she knows where to find all of the lost treasures. So I designed the costume to have many jewels and adornments. The tail is glamorous, made of jeweled pieces." The costume is worth five figures, according to SpikedSeltzer, because of the embellishments and craftsmanship. The neck and waist pieces are hand beaded with fresh water pearls and coral, for example.

Contestant winner Brittany Reid wearing the costume at Hulaween, a music festival in Suwannee, Florida. Photo: SpikedSeltzer The prize also included a consultation with Carter to personalize and style the look, and Reid's customized request was a blue headpiece. "The blue headpiece would be a true headdress," Carter says. "I wanted her to feel beautiful in her costume." Carter used some of the artisans she worked with on "Black Panther" to bead the mermaid costume, and "the jewels on the headpiece were handcrafted by the same jewelry designer that made the jewelry in 'Black Panther,'" she says.

Costume designer Ruth E. Carter at the Los Angeles World Premiere of Marvel Studios' "Black Panther" Jesse Grant | Getty Images Entertainment | Getty Images

Contest-winner Reid says her favorite part of the costume is the tail. "The tail is what makes each mermaid unique," Reid tells CNBC Make It. "The costume made me feel like I was on the set of a movie." Reid already wore the costume to Hulaween, a music festival in Suwannee, Florida, and she plans on wearing it on Halloween eve to a nightclub in Atlanta. After Halloween, she says she'll continue to wear the costume to visit hospitals, like the Children's Hospital of Atlanta, or to a fundraiser like Relay For Life (hosted by American Cancer Society, ACS) or Light The Night (hosted by Leukemia & Lymphoma Society, LLS) to take pictures with kids. "This would be a fun way to give back to organizations that give so much to the community," she says.