Sitting against a wall in John Spetrino’s collaborative arts workshop is a hulking metal beast powered by the dismembered pieces of old bicycles and constructed from old car parts. 

You may have seen it in the annual Kensington Kinetic Sculpture Derby and thought “How did he build that?”

If you ask, he’ll tell you. 

This weekend marks the 9th annual iteration of the derby, a celebration of hand-built human-powered sculptures that will travel the streets of Kensington. But behind the scenes of the event is a dedicated cadre of artists, craftspeople and amateurs who share information on construction techniques and where to find materials. 

“I didn’t know how to weld until I welded,” said Spetrino whose Frankford Avenue arts collaboration space is called Frank’s Kitchens. “Now I’m teaching people how to weld.”

Spetrino, who is not competing this year but will serve as one of the derby’s judges, isn’t the only one. Participants in the event have given lessons to help people build entries to the derby. That’s part of the effort to make the derby a city-wide event, but also part of the do-it-yourself ethic that has sprung up around the derby.

“I just want people to say, ‘Gee, I don’t have to be an engineer to do this,” said Joel Spivak, a South Philly artist who has given lessons for prospective participants. 

That attitude stands in fairly stark contrast to the Mummers, whose clubs have reputations for secrecy as they compete for prize money. 

“It’s very open, not very competitive,” said Spivak. 

The derby, which will be held on Saturday, is modeled on similar events held in Baltimore and northern California. Unlike those events, the Kensington derby is not a race. While the machines must be human powered, have wheels and cannot be pushed or walked, there aren’t a lot of hard rules. Likewise, there are prizes for the best breakdown, and best costume. 

Last year, Game of Cones, a replica ice cream truck that played the Game of Thrones theme song, won the People’s Choice award.

But the rules say that the floats -- or sculptures -- must be decorated with a consistent theme. And that’s where the collaboration ends, and where the secrecy begins. 

Dana Pavlichko and Steph Davis, part of a three-woman team whose drag-themed entries have won “best costume” three years, say they haven’t even told the event’s organizers what their costumes will look like this year. But if it’s anything like the past, they’ll draw attention. 

“Once you leave the house, it’s a series of very shocked reactions,” said Pavlichko.

The Philadelphia Federal Credit Union Kensington Kinetic Sculpture Derby & Arts Festival begins at noon on Saturday, May 16, at Trenton Avenue and Norris Streets and winds through the neighborhood. Visit kinetickensington.org for route information.