The vast majority of rockets fired by Hamas at Israel over the past month were made in Gaza using civilian materials, a senior Israeli military official said.
Over the course of the conflict, the de facto rulers of Gaza fired more than 3,300 rockets and mortar shells at Israel, with more than 500 rockets intercepted by the Iron Dome defence system, the Israeli military said.
"The vast majority of those launched were homemade. Only a small minority were Fajr 5 made by Iran," the anonymous official said on Thursday.
The Gaza manufacturers of these rockets used "water pipes" of different diameters for the bodies of the rockets, filling them with explosives made from materials such as products used in agriculture, the official said.
Hamas adapted to manufacturing its own weapons after Egypt cracked down on smuggling through tunnels in the Rafah area into the Palestinian enclave, the official said.
Outsiders had in the past taught Gazans how to build the weapons, while some Gazans went to other countries in the region, including Syria and Iran, to learn more, the Israeli official said, estimating some 150 people in Gaza were directly involved in producing projectiles.
Hamas surprised Israel during the campaign that began on July 8 with its armed resistance to the Israeli military experts have said, and had sought to make political gains in negotiations in Cairo on a long-term truce.