TAL RIFAAT, Syria — As the midsummer sun blazed over this partially deserted Syrian city one recent afternoon, two young men appeared in a pickup truck in an alley near several auto repair workshops. Protruding from the truck’s bed was a steel pipe about three feet long and two and a half inches wide, resting on a simple frame.

The pipe was not for plumbing. It was a locally made mortar that had been used in July in the battle for Azaz, a city in northern Syria where antigovernment fighters drove away the army of President Bashar al-Assad.

“Now we have three or four of these, but we need to make more,” said Mustafa, one of the men who had assembled the weapons in small machine shops where since last year a key aspect of the revolution against Syria’s government has been waged by men who do not themselves often carry guns.

Mustafa’s handiwork, which also includes the manufacture of homemade mortar rounds (“We can make, every day, 25 shells,” he said), is part of a grass-roots effort to create the fighters’ diverse and idiosyncratic arsenal. That is an essential component of the rebels’ survival and their recent successes against the professionally trained military with which they are locked in a struggle for Syria’s future.