Michael Saiger doesn’t smoke e-cigarettes, but many of his friends like Juul, so he began to tinker with designs to make it feel more elegant.

“Back in the day, people used to have a beautiful Cartier lighter, or a really cool monogrammed lighter,” said Mr. Saiger, the founder and creative director of Miansai, a jewelry company known for men’s bracelets. “I wanted something that feels nostalgic paired to something that’s new and modern.”

Last month, Miansai began selling a handcrafted 18-karat gold case designed to slip over Juul’s e-cigarette device. The cost of the Juul itself? About $35. The cost of the gold case? $5,000.

Mr. Saiger’s blingy design represents the very high end of a burgeoning marketplace for so-called skins to dress up an off-the-shelf vaporizer. Dozens of companies sell wraps for e-cigarette devices through eBay, Etsy, Amazon or their own websites. They include Eonsmoke, Juul Necessities and J-Wraps, which allows for the option to design your own skin.