There was the necklace he designed with a compartment for human ashes, the custom-crafted magic wands, the ring made out of gold fillings from a client's dead grandmother's teeth, and the large stainless steel hook for the man in the rock band who lost his hand.
Manthey, 69, of Grays Ferry, even made his own articulated thumb out of silver - replete with an expertly manicured nail - after he sawed the tip of his natural-born thumb off during a construction accident at a yoga studio 15 years ago.
"Total strangers approach me at Reading Terminal and on the bus asking, 'What is that?' " Manthey said of his shiny silver digit. "What it is, is shameless self-promotion."
In past lives, Manthey made his living as a commercial diver, nude model, nurse, Greenpeace employee, construction worker, bicycle courier, and videographer, but for the last 29 years he's been a jeweler, creating one-of-a-kind pieces inspired by the underwater world he saw as a diver.
Manthey - who looks equal parts Jeff Bridges and Claude Monet - rides around on his bicycle. His statement jewelry, his long gray-and-white hair, his thick German accent, and his wild white eyebrows make him conspicuous wherever he goes.
"He's got a reputation for being a bit of a character, which I'm sure he cultivates," said Manthey's son, Till, who was named after a traveling Dutch jester from 16th-century literature.
A native of northwestern Germany, Michael Manthey hitchhiked across Europe, the Middle East, and North Africa after graduating from high school.
While living in Morocco, he made small leather bags for money. While in the Grand Canary Islands, he picked up scuba diving to help salvage a shipwreck.
When Manthey returned to Germany, he was certified in underwater construction and photography before moving to Hamburg, where he met his son's mother, an American who worked as a pantomime.
When she was pregnant with Till, the couple moved to the United States, eventually settling in Philly when Manthey got a commercial diving job.
But when he "ran afoul of the diving mafia," Manthey took the video equipment he'd been using in the water and brought it to the stage, filming productions and audition tapes for performing artists.
Around the same time, he began working as a fund-raiser for Greenpeace, earning the nickname "Mr. Double Quota" because of his ability to outpace fund-raising goals.
But then Manthey broke his neck in a boating accident and was put in a halo neck brace for six months.
"I was thinking my life was over," he said.
In a moment of desperation, Manthey began free-form doodling, creating a drawing that seemed so three-dimensional he thought it might lift off the paper.
"I realized for the first time in months I didn't think about my own personal misery," he said.
Revitalized by the creative process, Manthey put tiny rearview mirrors on his neck brace and started riding his bicycle again as he began his next journey, to become an artist.
Manthey eventually discovered his love for jewelry-making using lost-wax casting.
He worked endless craft shows, setting up his jewelry at a booth he called "Heavy Metal." Then he created more elaborate pieces that he exhibited in galleries and art shows in Philly, New York, and Chicago.
Today, Manthey works in relative obscurity in the second-floor studio at his Grays Ferry home, where signs on the front door read: "Welcome to Knowhere," "Doing Strange Things in the Name of Art," and, in Chinese characters, "Old man who turns s*** into gold."
Manthey doesn't have a computer or a television or even a couch (we sat on a coffee table covered by a small rug for this interview), but he's got his art and his son and several lifetimes' worth of adventures.
"Happiness is a very fickle thing, but I am content. I feel I am where I am supposed to be, doing what I am supposed to do," he said. "And let me tell you, that is a privilege."
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