R&M has outlasted its original competitors. And while demand is down, R&M still does the porch enclosures, also known as birdcages, that are a common way to simultaneously protect and decorate houses in Camden's Latino neighborhoods.
"I like having my own company," says Gonzalez, who also makes custom dune buggies. "I can build you a little handrail or a three-story fire escape ladder. I'm a creative guy."
Not bad for somebody who arrived in Camden from Utuado, Puerto Rico, without much money and even less English in 1990.
But simply saying that the Gonzalez family worked their way up doesn't do justice to their early days, when dinner was sometimes a couple of Cooper River catfish.
"I got a job as a helper at a place in Camden that built security gates," Gonzalez says. "They did welding, and I said to myself, 'Let me see how this little spark thing works.' "
After three years, he had learned enough about welding to start his own business. He was a sole proprietor, working from his backyard; later he partnered with his younger brother, Edwin, in rented quarters on 27th Street.
Edwin didn't like New Jersey's climate, and went back to Puerto Rico. But Gonzalez kept at it, fabricating his own tools and machinery.
He canvassed city neighborhoods for work. He left his business card with strangers.
In 2002 he graduated from an entrepreneurial training program offered by the city's Latin American Economic Development Association, which over the last 27 years has helped more than 500 small businesses get started in Camden. R&M is among the success stories, president Raymond Lamboy says.
By 2005 Gonzalez and his wife were negotiating to buy a firm that had been in business, under a succession of owners, since the 1930s. Renamed R&M, the company had its best year in 2008, when it had seven employees and two trucks on the street.
But the recession took a chunk out of the business, and the cost of materials rose. A "belly porch" - so called because the distinctive outward bulge in the vertical bars suggests a pregnant profile - now can cost as much as $2,000, out of reach for many in Camden.
Nevertheless, "I don't stop," Gonzalez says, sitting in the front office on 23d Street with his wife, with whom he has six children. Their middle son Ramon Jr., 24, works at R&M along with his parents.
Persistence has paid off; R&M has become something of a brand name in the city.
"He does a lot of work for me" as a subcontractor, says Emerson Hill, who owns a city firm called EJ Hill Contracting. "Anything I ask him to do, he always comes through."
"We love working with him, with a family firm in the city," says Betsy Clifford, executive director of the Camden Lutheran Housing Corp.
The nonprofit builds affordable houses and apartments, mostly in North Camden. R&M, she adds, "does excellent work."
Gonzalez says he's particularly proud to see his fences, gates, and porches holding up well.
"I'm not rich," he says. "But I never dreamed about being a millionaire."