A streetball legend, Joe Hammond, who is better known by his nickname the Destroyer, said the New York rims were so tricky that he became focused on having his shots avoid them altogether, refusing to count points if the ball touched steel. “One thing about playing on the rims in the parks: you learn to adjust,” Mr. Hammond said.

Image John Fitzgerald, a blacksmith for the New York parks department, with a finished rim. Credit... Fred R. Conrad/The New York Times

But even in New York, the forging of rims may be an endangered art. Some of the city’s most celebrated courts, like Rucker Park in Harlem and the West Fourth Street Cage in the West Village, have made the switch to prefabricated rims, in part because the players there expect modern equipment. And when a new park is built or an existing one receives a full rehabilitation, a prefabricated rim is installed.

The prefabricated rims are not only more up to date, but they are also less expensive  typically costing other cities less than $60, compared with about $90 for the handmade rims, which includes about $65 for labor.

But officials from the city’s Department of Parks and Recreation say the handmade rims stand up better to the demands of New York players, so they will continue to be produced  at least to replace those that have been stolen or, in rare cases, damaged. (The rest of the time blacksmiths occupy themselves with an assortment of other tasks, like repairing park fences and building lifeguard chairs.)

“We have found its more economical to make them because they’re stronger, they last longer,” said Jim Cafaro, the deputy chief of technical services for the parks department. “So it’s cost-effective to do this.”

The design, which parks officials said was of unknown provenance, has been kept in a dusty composition notebook in the center of the cavernous workshop on Randalls Island underneath the Robert F. Kennedy Bridge, where 92 rims were made last year. The blacksmiths are in the process of vacating the 80-year-old building, so production of the rims has been temporarily suspended.

The machinery and tools, including the old anvil, will be moved to a new location. Left behind will be the old hoop that hangs over an oil-stained section of the shop, used for years of lunchtime games. “You have to have a nice touch for them because they’re solid,” said Eugene Desplantes, a metal worker who starred in those daily battles. “They’re not forgiving.”