In the case of Hamas, the US and Israel are the primary weapon manufacturer, as unexploded ordinance is the primary source of their explosives.
https://www.nationalreview.com/corner/hamas-is-using-unexplo...
https://www.nationalreview.com/corner/hamas-is-using-unexplo...
This is an explicit ideal in the 'Resistance Axis', to develop the ability to produce military equipment locally and not be dependent on brittle trade routes or smuggling.
The West Bank seems to get rifles from several sources, both american style that probably comes from PA or IDF and russian style, probably smuggled through Jordan from Iraq, Iran, Russia. They produce IED:s locally, quite crude ones, not the directed type with concave copper plates favoured by iraqi militias. Eventually they'll learn to make those too, I'm sure.