Hamas builds their own rocket propelled grenades and anti-tank missiles, and morter launchers out of plumbing pipes. They have some US made weapons from Afghanistan and Ukraine. But mostly the imported weapons are of Soviet manufacture that are claimed to have been modified by Iran. They also copy weapons: Their Shabab drone is a copy of the Iranian Ababil-2. I think they take any weapons they can get, and most of the world is behind them so they get weapons from all sorts of places, including Russia and Iran. I"ve heard they have some from North Korea and China too.