The unveiling marks the 25th anniversary - plus one day, for sticklers of fact - of the return of full cable car service after the city's aging system was shut down for nearly two years to undergo a major overhaul.

Cable car No. 15 is no off-the-shelf vehicle.

For more than five years, nearly 30 Municipal Transportation Agency crafts workers - carpenters, a patternmaker, metal workers, transit mechanics, welders and painters - labored on and off to build the cable car from scratch, working off blueprints more than a century old.

They started by laying down the I-beams, then built the floor, the frame, the elaborate curved roof. Next came the mechanical components. Included is the grip, which grabs the cable that tows the cars up and down the city's hilly streets at a steady clip of 9.5 mph.

The final stop was in the paint shop at the cable car barn and powerhouse on Nob Hill. There, No. 15 was brought to life with paint hued yellow, red, white, buff, gray, black and maroon - a color scheme that originated on the Powell-Mason line in the 1890s. The bell, an auditory icon in San Francisco, sits atop the roof, ready to be broken in by the gripmen.

"It's a work of art," Christopher Hill, Muni's manager of cable car maintenance, said of the new 8-ton rolling monument.

"When we get a car like this, it's a blank canvas," said Larry Harris, one of three Muni painters who have worked on the project - when time permitted - since it arrived in their shop early last year. "We wanted to make sure we got it right. There are going to be a lot of people looking at this."

Ken Russi, another on the paint crew, said a lot of pride goes into the work. Late last week, he was going over No. 15 inch by inch with his eye as a trained graphic designer and the paint brush of his trade doing touch-ups.

"Once it goes into service, I won't want to look at it anymore. It will get destroyed," said Russi, a 34-year Muni veteran. A San Francisco native who grew up riding the cable cars, he knows the wear and tear they endure as they haul tourists and sentimental San Franciscans.

Like the others who worked on No. 15, Russi and Harris plan to sign the cable car in places not seen by the riding public. The tradition of crafts workers leaving their mark dates back more than 100 years.

Made of bronze, steel, red oak, white oak, knot-free fir, Alaskan yellow cedar, canvas and glass, No. 15 cost $823,000 to build. Just about the only materials not specially fabricated for the cable car were the lightbulbs, hinges, rope and screws.

No. 15 is the 12th cable car produced from the bottom up by Muni in the past two decades. It will be used on the Powell Street lines that run from Market Street downtown to Fisherman's Wharf.

The new cable cars ensure that the 136-year-old system - a designated National Historic Landmark and the only one remaining in the world that operates on public streets - will carry on. The average lifespan of a cable car is about 100 years.

No. 15 made its test run after the morning rush hour on June 10 with eight or nine Muni workers aboard to make sure it was safe and sound. The crew deemed the trial a success. As expected, the new cable car ran a little stiff, reports Hill, the maintenance manager who was on the first ride. "It's going to take a little time to loosen up."

E-mail Rachel Gordon at rgordon@sfchronicle.com.

This article appeared on page B - 1 of the San Francisco Chronicle