LAKE GOODWIN — It took most of a lifetime for Donald Passow, 96, to create his one-of-a-kind motor scooter.

As a teen on a Wisconsin farm, he started to build a kind of precursor to the Vespa, from plans he found in a magazine: bike parts, chain sprockets and oak planks. He abandoned it when he left for Europe, to be a fighter plane mechanic in World War II.

Later, he became an architect, with a head full of inventions. He designed his house, a maze of triangular rooms with no hallways, on the west shore of Lake Goodwin. He drafted the scooter in his 80s. It’s collapsible, brushed aluminum, battery-powered. A friend turned the blueprint into a prototype, dubbed the Lo-Go Motion, at a cost of $3,300. The Daily Herald ran a front-page article on it in 2011.

On a crisp fall morning in late October, Passow strolled outside to pick up his newspaper. He glanced at his carport.

The scooter was gone.

“It’s so hurtful,” said Passow, who believes it was stolen overnight. “It’s just, I put so much into this over the years, you know? So much promise here and potential. If I could’ve got some company interested in it, they could’ve built it, sold it, like they do with Vespa scooters. To take the prototype? It’s hard to promote this now.”

Passow saw a market for the Lo-Go Motion, a lightweight scooter that packs down small. It used two batteries, no gas. You could put it in a motorhome. You could put it on a boat. Heck, you could put it on a small plane. Once you got to your campsite, or dock, or airstrip, you’d unfold the scooter and it would motor you to your next stop.

Since the Herald article ran six years ago, time has slowed down Passow. Under his living room is a built-in hangar where he kept his sea plane, a Lake Buccaneer. He sold it sometime after his wife died. It wasn’t fun anymore. Now he lives alone with a small dog, Ginger. On his kitchen table he keeps a black three-ring binder with a handwritten label, “Designs and Inventions.” One is a multi-tool, like a Leatherman, but made for one-handed use. Another is a lamp affixed to his house, with long flexible pipes that swing out like a giant arm.

He lost track of how much time he spent working on the scooter. Loosely, the dimensions were based on the Power Mouse model he found in a Popular Mechanics magazine from 1938. But that was gas-powered. Comparing the two side-by-side, about the only thing they have in common is the number of wheels.

“It’s so unique that if you see it, you know it,” Passow said. “There’s only one out there.”

Passow hopes that uniqueness will bring it home, if it shows up at a pawn shop, in a scrapyard or on Craigslist.

Grill slits line each side of the boxy silver body. Blue wheels, blue handlebars and blue suspension accent the chassis. A wide fender and a wide bumper curve over small, fat tires. The padded seat can be boosted or lowered to adjust for height. There’s room for two.

Over the past few months Passow had started to run endurance tests again. He wanted to see how far it could go. He never took it far enough to run down the 12-volt batteries all the way. He didn’t have a speedometer on it, but he bets the Lo-Go Motion topped out at 30 mph. That sure beats walking, he said. So he was satisfied with it. He’d park it between two Volkswagens outside his home. He never saw a need to take out the key. Over the 31 years he has lived at Lake Goodwin, he said, nothing has ever been stolen from his home.

Passow wonders why someone would take something that meant so much to him. He hasn’t heard from police since he made a report. He has offered a $3,000 reward for information leading to the scooter’s recovery.

Tips can be directed to the Snohomish County Sheriff’s Office at 425-388-3845.

“I can’t replace it,” Passow said, “and I’m too old to start again.”

Caleb Hutton: 425-339-3454; chutton@heraldnet.com. Twitter: @snocaleb.